HPS SoC Boot Guide - Cyclone V SoC Development Kit

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AN-709 | 2016.01.27

HPS SoC Boot Guide - Cyclone V SoC Development Kit

Introduction

This document describes:

An overview of the boot options available on the Cyclone^® V
Recommendations to help reduce the boot duration, including measurements of the boot process on the Cyclone V Development Kit
Recommendations to help with debugging the boot process
Bare-metal boot examples that can be run on the Cyclone V SoC Development Kit

Note: Although the document targets Cyclone V, it also applies to Arria^® V, since the HPS portion is identical between the two families.

Prerequisite

In order to run the examples presented in this Boot Guide the following are required:

Altera^® Cyclone V Development Kit, Rev D
Host PC running Windows 7 or newer¹
Altera SoC Embedded Design Suite (SoC EDS), v14.1 installed
Altera Complete Design Suite (ACDS) v14.1²

Note: This document assumes a basic knowledge of Altera SoC EDS, ACDS, Preloader Support Package Generator (part of SoC EDS) and ARM DS-5 AE.

¹ Linux can also be used, with similar commands.

² Required only for the boot from FPGA example.

Boot Overview

This chapter presents an overview of the different boot options and capabilities available for the Cyclone V.

Boot Flow

The following figure depicts the typical boot flow:

Figure 1. Typical Boot Flow

Additional boot flows are possible, as shown in the following diagram:

Figure 2. Additional Boot Flows

As it can be seen in the above diagram, we always have the Boot ROM, but then we may have more or less stages, depending on the system design.

Boot ROM

The HPS boot process starts when the processor is released from reset, and jumps to the reset vector address, located in the Boot ROM address space.

Typically, the main responsibilities of the Boot ROM are:

Detect the selected boot source
Perform minimal HPS initialization
Load the next boot stage (typically the Preloader) from Flash to OCRAM and jump to it

The behavior of the Boot ROM is influenced by the BSEL and CSEL options, and also by the registers in System Manger (for RAM boot) as shown later in the document.

For the scenarios where the next boot stage is located in Flash, the Boot ROM can use up to four different images:

On Cold reset, the Boot ROM always starts with the first image, and checks the CRC. If the CRC is OK, then it passes control to it. If the CRC is not OK, then it tries the next image and so on. Before an image is passed control, the Boot ROM updates the register sysmgr.romcodegrp.initswlastld with the image index.
On a Warm reset, the Boot ROM looks at the register sysmgr.romcodegrp.initswstate for the magic value 0x49535756. If it is there, it means last Preloader executed OK, so it loads it again and executes it. If the magic value is not found, it means the previous Preloader was not OK, and the Boot ROM will advance to the next image and increment sysmgr.romcodegrp.initswlastld.
If all images are exhausted, the Boot ROM will try to fallback on the FPGA image. It will continue to be reset by the Watchdog, but will never try to boot from Flash until the next Cold reset.

Note: The BootROM requires a special header to be placed at the beginning of the images that need to be loaded from flash. The header also contains a checksum that is used for validating the image. The header can be attached to the image by using the mkpimage tool that is included with the SoC EDS.

Preloader

Typically, the main responsibilities of the Preloader are:

Perform additional HPS initialization
Bring up SDRAM
Load the next boot stage from Flash to SDRAM and jump to it

Currently, two different Preloader options are available:

SPL – part of U-Boot. Provided with SoC EDS under GPL (Open Source) License
MPL – provided with SoC EDS as an example using the HWLibs (Altera bare-metal libraries). Uses BSD license.

Note: The Preloader requires a special header to be placed at the beginning of the next stage boot image. Also, the header contains a CRC value used to validate the image. The header can be attached to an image by using the mkimage utility that is included with the SoC EDS.

Bootloader

The Bootloader has typical responsibilities that are similar with the Preloader, except it does not need to bring up SDRAM.

Because the Bootloader is already residing in SDRAM, it is not limited by the size of the OCRAM. Therefore, it can provide a lot of features, such as network stack support.

Boot Sources

The HPS can boot from one of the following sources, as selected by the BSEL pins:

SD/MMC
QSPI
NAND
FPGA

The following table presents the possible BSEL options, together with the actual jumper settings on the Cyclone V Development kit, rev D:

BSEL	Description	Cyclone V Dev Kit Switches
BSEL	Description	J28:BSEL0	J28:BSEL0	J28:BSEL0
0	Reserved	Right	Right	Right
1	FPGA	Left	Right	Right
2	1.8 V NAND	-	-	-
3	3.3 V NAND	-	-	-
4	1.8 V SD/MMC	-	-	-
5	3.3 V SD/MMC	Left	Right	Left
6	1.8 V SPI or quad SPI	-	-	-
7	3.3 V SPI or quad SPI	Left	Left	Left

There are four boot options:

Indirect execution - When booting from flash (SD/MMC/QSPI/NAND):
1. The code is loaded by the Boot ROM from the flash to the OCRAM.
2. Run the code from this location
Direct execution - When booting from FPGA, the Boot ROM simply jumps to an address in the FPGA address space.
FPGA fallback boot - If the selected boot mode fails, the Boot ROM will try to jump to a fallback image in the FPGA, if it exists.
RAM boot - If an Warm Boot, the System Manager can be configured so that the Boot ROM directly jumps to a location in OCRAM.

Boot from SD/MMC

When booting from SD/MMC, two different options are available:

Raw mode - Preloader images are located at address0 on the card.
Partition mode - Preloader images are located at offset 0 on a custom partition with ID=A2 on the card.

Figure 3. Raw Mode and Partition Mode Options

The MBR is a 512 byte data structure, located at address 0, describing the partitions existing on the SD/MMC card.

The Raw mode does not allow the card to be partitioned, since the Preloaders are located at address 0, where the MBR data structure needs to be placed.

When using the Partition mode, the Preloader is located on a custom partition that does not interfere with the other partitions on the SD/MMC card. The other partitions could, for example, contain Windows FAT, or Linux EXT2 or EXT3 file systems, providing more flexibility for the overall system design.

Boot from QSPI

When booting from QSPI, the four Preloader images are always located at the beginning of the QSPI address space, occupying a total of 256 KB.

Figure 4. QSPI Address Space

Boot from NAND

When booting from NAND, the Preloader images are located at the beginning of the flash. Each image has to start at NAND flash block boundary.

Figure 5. NAND Flash Block

Note: Booting from NAND is not available on the Cyclone V Development kit.

Boot from FPGA

When booting from FPGA, the Boot ROM performs the following operations:

Waits for FPGA to be configured and in user mode
Verifies that the Boot from FPGA was enabled in the FPGA fabric
Jumps to address 0xC0000000, corresponding to offset 0 on the HPS-2-FPGA bridge

Note: The configuration on the FPGA side needs to enable the signal notifying the HPS that a boot image is available (f2h_boot_from_fpga_ready).

Note: No other checking, such as CRC of the image, is performed. No clocking configuration is performed either, and the CSEL value is ignored.

FPGA Fallback Boot

When the Boot ROM did not successfully load any image, it tries to boot from an FPGA fallback image:

Checks if the FPGA is configured and in user mode
Verifies that the fallback image was enabled in the FPGA fabric
Jumps to address 0xC0000000, corresponding to offset 0 on the HPS-2-FPGA bridge

Note: The configuration on the FPGA side needs to enable the signal notifying the HPS that an FPGA fallback image is available (f2h_boot_from_fpga_on_failure).

Boot from RAM on Warm Reset

This scenario applies only for Warm resets. The Boot ROM can be instructed to directly jump to an image already loaded in OCRAM with an optional CRC check for that image.

The following registers located in sysmgr (romcodegrp and warmramgrp) are used to set up the Boot from RAM on Warm Reset:

enable - Set bit 0 to enable Boot from RAM on Warm reset.
datastart - Byte offset in OCRAM for the region to be CRC-validated. Needs to be 4 byte aligned.
length - Size of OCRAM area to be CRC-validated, in 4 byte words. Set to 0 to disable the CRC validation.
execution - Byte offset in OCRAM where to jump to.
crc - CRC value for the OCRAM area that is CRC-validated.

Note: When booting from RAM, the Boot ROM does not do any initialization, including clocking and it therefore ignores the CSEL pins.

Boot Clocks

The board on which the Cyclone V resides can have different clocking needs:

OSC1 input clock can have different values
Flash memories can have different clocking requirements
Board layout may also impact the maximum flash speeds

In order to accommodate the above, the Boot ROM can be instructed to use different clocking options, through the CSEL pins. The following table presents the CSEL options available on Cyclone V, together with the actual jumper settings on the Cyclone V Development Kit, rev D:

Table 1. CSEL Options Available
CSEL	Cyclone V Dev Kit Switches
CSEL	J26:CSEL0	J26:CSEL1
0	Right	Right
1	Left	Right
2	Right	Left
3	Left	Left

Note: In the following cases the Boot ROM does not touch the clocking at all:

CSEL = 0
Boot from FPGA
Fallback boot from FPGA
RAM boot on Warm reset

Boot Duration

In some applications, the duration of the boot process is very critical, and it needs to meet a certain constraint.

This section presents some considerations on optimizing the boot time, together with some measurements taken with various options on the Cyclone V Development Kit.

The elements that compose the boot time for a typical Linux system are depicted in the figure below:

Figure 6. Boot Time Stages for Linux Systems

A typical bare-metal application boot time is depicted in the following figure:

Figure 7. Boot Time Stages for a Bare-Metal Application

Note: The above figures are not drawn to scale - each stage is depicted with the same size.

Optimizing Boot Duration

The recommended approach for optimizing boot time consists of:

Measure the duration of the total boot time. For example, monitor the reset signal and a custom signal toggled at the beginning of the application by using a scope or a logical analyzer.
Measure the duration of as many individual steps as possible, to understand where most of the time is spent.
If possible, optimize the steps that take most of the time. Usually the upper levels take longer than the lower ones.

The following sections describe some of the factors that influence the duration of the Boot ROM.

Hardware Powerup Sequence

This is the smallest contributor to boot time and it does not need to be optimized. It is actually influenced by the OSC1 input clock frequency, but it is so small that its duration does not warrant changing the OSC1 value.

Boot ROM

The duration of the Boot ROM is influenced by the following factors:

OSC1 Clock Frequency (for the portion before setting the PLLs or when using CSEL=00)
Clocking option (selected by CSEL pins)
Boot Source (SD/MMC, QSPI, NAND or FPGA – selected by BSEL pins)
Performance of external flash device
Size of Preloader image

The above parameters can be tweaked in order to optimize the Boot ROM duration. For example, the OSC1 and CSEL should be selected such that the maximum possible clock values are used for both the MPU and the external flash.

Another example - Tweaking the Preloader so that it is made smaller. The smaller the Preloader, the less time the Boot ROM spends loading it from flash.

For the boot from FPGA option, the Preloader loading time is reduced to zero. But the FPGA has to be already configured for this to be possible, and this takes time, as well.

Preloader

The Preloader duration is influenced by the following elements:

Location of next boot stage
Size of next boot stage image
Speed of SDRAM (since Preloader loads the image from Flash to SDRAM)
Speed of Flash
Various Preloader options:
- SDRAM scrubbing
- Hardware diagnostic
- Checking the CRC of the next boot stage image
- Serial logging
- Program FPGA

In order to reduce the Preloader duration, the above parameters may be tweaked. For example:

Reduce the size of the next boot stage (for example remove networking support from U-Boot if not needed)
Use a faster flash (it will require changing Preloader source code – option is not available in Preloader Generator)
Disable hardware diagnostic if enabled (uncheck HARDWARE_DIAGNOSTIC in Preloader Generator)
Disable serial console output - (uncheck SERIAL_SUPPORT in Preloader Generator)
Disable CRC of the next boot stage image (uncheck CHECKSUM_NEXT_IMAGE in Preloader Generator)

If the FPGA programming is selected in the Preloader, then the following also impacts the duration:

Location of FPGA Image (QSPI or SD Card FAT partition)
Size of the FPGA Image (compression may reduce it significantly)

Bootloader

The duration of the Bootloader is influenced by the following:

Size of the next stage to be loaded (Linux kernel for example)
Location of the next stage (flash, network, etc)
Whether networking is enabled, and is statically or dynamically (DHCP) configured
Whether FPGA programming is also performed
Speed of SDRAM
Countdown counter³ (default 5s in U-Boot – can be disabled for production systems)

³ Can be tweaked to achieve faster boot time.

Linux Kernel

The Linux kernel can be made to start faster, and there is a lot of material in the Linux community on how to achieve this. For example, removing debugging capabilities and various unneeded drivers and features.

Init Scripts

The boot time can be optimized by reducing the amount of work done in the init scripts. Either remove unneeded functionality, or defer it for later, if possible.

Boot Duration Measurements

This section presents various Boot time measurements taken on the Cyclone V Development Kit. Only Boot ROM and Preloader are measured.

The measurements are done with the following setup:

SoC EDS 14.1b182: for GHRD & Preloader
Cyclone V Development Kit rev D
Kingston 4GB Class 10 SD card
512 MB Micron QSPI
Preloader size = 38,548 bytes
U-boot size = 238,316 bytes

Note: All durations are in milliseconds.

Table 2. Boot ROM Duration for CSEL Options. This table presents the Boot ROM duration for different `CSEL` options, for both SD/MMC and QSPI.
Source	CSEL=00	CSEL=01	CSEL=10	CSEL=11
SD/MMC	168.86	N/A	72.43	103.06
QSPI	110.44	28.09	24.56	13.9

Table 3. SD/MMC and QSPI Preloader Duration . This table presents the standard Preloader duration, for both SD/MMC and QSPI.
Source	CSEL=00	CSEL=01	CSEL=10	CSEL=11
SD/MMC	142.88	N/A	136.67	137.17
QSPI	136.4	130.94	130.84	130.27

Note: The CSEL also influences the Preloader duration, but less than Boot ROM.

Table 4. Preloader Duration after Removing Serial Support . This table presents the Preloader duration after the serial support was removed:
Source	CSEL=00	CSEL=01	CSEL=10	CSEL=11
SD/MMC	93.58	N/A	87.26	87.81
QSPI	79.08	73.27	73.08	72.53

Table 5. Preloader Duration after Removing Serial Support and the CRC. This table presents the Preloader durations after removing both the serial support and the CRC of the next boot stage.
Source	CSEL=00	CSEL=01	CSEL=10	CSEL=11
SD/MMC	71.25	N/A	65.04	65.48
QSPI	56.44	50.61	50.82	50.25

Table 6. Boot ROM and Preloader Durations when Using SD/MMC with a FAT Partition. This table presents the durations of Boot ROM and Preloader when using SD/MMC with a FAT partition for the next boot stage.
Note: The new Preloader size is 42,268 bytes.
Source	CSEL=00	CSEL=01	CSEL=10	CSEL=11
BootROM	183.85	N/A	78.23	113.80
Preloader: SD + FAT	78.56	N/A	75.65	75.93

Note: The serial support and the CRC for the next image area also removed.

Table 7. Duration of FPGA Programming. This table presents the duration of FPGA programming, when performed from Preloader. The uncompressed FPGA image size is 7,007,248 bytes, while the compressed FPGA image size is 2,335,334 bytes.
FPGA Image Source	Uncompressed Image	Compressed Image
QSPI	1,374	473
SD-FAT	563	223

Table 8. Duration of Two of the Optional Preloader Operations
Activity	Duration
Hardware Diagnostic (Memory Test)	2,640
SDRAM Scrubbing (16 MB)	25

Boot Debugging

This section presents some techniques that can help with the debug of the booting process. Considerations are included for Boot ROM and Preloader. The rest of the boot flow is generic and can be debugged with general purpose techniques.

Boot ROM

Since the Boot ROM is the first booting stage, the most common boot failure symptom is that not anything is happening. For example, the system does not boot, there is no activity on the UART from the Preloader (if enabled).

The first thing to try when having boot problems is to check the Cold boot. The Warm boot is a little more versatile, but depending on how the software configures the chip, it may fail in different ways. Cold boot is initiated by either pressing the Cold reset button (if available) or by power-cycling the board or the device.

The following may cause the Warm boot to fail, but not the Cold boot:

Application software enabled Warm RAM Boot incorrectly
Application software changed the Warm reset options inconsistently with the usage scenario
QSPI is used as a boot source, but the QSPI is not reset on a Warm reset, as required by Boot ROM for some QSPI devices with more than 16 MB of Flash

Another thing to check is whether the HPS works at all. This can be done by connecting a debugger (if the JTAG connection is available on the board). If the debugger can connect reliably, then probably the HPS is fine.

If a debugger connection is available, more information can be obtained by connecting a debugger to the board and looking at registers maintained by Boot ROM and Preloader to determine what happened. The registers are available in sysmgr.romcodegrp and consist of:

initswstate - The Preloader writes the magic value ‘0x49535756’ to it just before it jumps to a valid next boot stage. The absence of that value means that Preloader did not jump to the next boot stage.
initswlastld - Contains the index of the last Preloader software image loaded by the Preloader from the boot device. There are a total of 4 Preloader images.
bootromswstate - Information about the BootROM state, including:
- Bit 0: if set, it means that the BootROM tried all four images and none of them worked
- Bit 1: set if the Preloader was started (then it may have failed)
- Bits 11:8: which flash boot source was used:
  - NAND: 0
  - SD/MMC: 1
  - QSPI: 2

Note: The contents of bootromswstate may change in future revisions of the BootROM.

If a debugger connection is not available, and boot from Flash is requested, then the flash signals could be monitored for activity, if available for observation on the board. If there is some activity on the flash lines, then probably HPS is OK.

If it is still not clear whether the HPS is OK, then the power, clock and reset signals could be verified. Check the power supplies for the correct voltages, absence of excessive noise and also power up sequencing. Use a scope to look at the input clocks, for amplitude, frequency and excessive jitter. Look at the reset signals to confirm they are correct.

If the HPS is OK but the Boot ROM does not seem to successfully load the Preloader, it may be because one of the following reasons:

Preloader images are corrupted in Flash, and the Boot ROM cannot load any of them.
Preloader images are correct in flash, but communication with the Flash fails.
Preloader is loaded correctly, but it does not do what we expected it, or crashes because of a software bug.

In order to reduce the likelihood of Flash communication issues, CSEL can be set to 00, if configurable on the board. This prevents Boot ROM from reprogramming the PLLs and also forces it to use the lowest possible speed when communicating with the Flash device.

The flash lines (if available) could be monitored with an oscilloscope and/or logical analyzer, looking for things like:

How long is the communication? Does the Boot ROM give up on communication quickly, or there is a lot of communication? If it gives up easily, it may be an indication that the problem is pretty obvious.
Do the signal levels look correct? Look for voltage levels, ringing, raise and fall times.
If using logical analyzer, and option is available, try to decode the communication between the HPS and the flash device and see if and how it is failing.

If the above steps are not enough to diagnose the issue, and a debugger connection is available, the contents of the upper 4 KB of OCRAM can be dumped from the debugger and it can be analyzed by Altera. This can lead to information such as “Boot ROM failed to initialize SD Card”. Most of the time, the same information can be obtained by looking at the external behavior and at the above mentioned registers.

Preloader

The Preloader can be debugged much easier than the Boot ROM, since all the source code is available.

The following general purpose debugging techniques can be used:

On systems where a JTAG connection is available, a debugger can be used to debug the Preloader.
Alternatively, the code can be modified to output more debug information either through serial connection, if available, or by toggling LEDs or various other signals.

When the Preloader is generated by the Preloader Support Package Generator, the file preloader.ds is also automatically created. This file enables the developer to debug the Preloader by using the ARM DS-5 AE over a JTAG connection.

Note: Since the executable is an ELF format, any other compatible debugger may be used too.

Debugging the Preloader from ARM DS-5 AE

The following steps are required in order to debug the Preloader from ARM DS-5 AE:

Compile Hardware Design to obtain the handoff files.
Generate the Preloader from the Preloader Support Package Generator. This will create the files preloader.ds and uboot.ds in the Preloader folder.
Compile the Preloader to obtain the executable.
Connect the board to the host PC by using the USB serial connection (in order to see the Preloader serial output).
Connect the board to the PC by using either USB Blaster or ARM DSTREAM.
Start ARM DS-5 AE and select your workspace if asked.
In DS-5 AE, go to Run > Debug Configurations to open the Debug Configurations window.
Create a new debug configuration by right-clicking DS-5 Debugger on the left panel and selecting New.
Rename the new debug configuration to Debug Preloader by editing the Name field.
In the "Connection" tab of the Debug Configuration window, select the target to be Altera > Cyclone V SoC (Dual Core) > Bare Metal Debug > Debug Cortex A9_0.
Select Target Connection to be either USB-Blaster or DSTREAM.
Click the Browse button in the "Connections" group, select the desired connection, and click Select.
In the "Debugger" tab of the Debug Configurations window, select the option Connect Only under "Run Control".
In the same tab, check the option Run debug initialization debugger script, then click File System … button and browse to the preloader.ds file that was created by the Preloader Generator .
Click the Debug button. This will close the Debug Configurations window, and start a debugging session. The usual debugging techniques can then be applied.

U-Boot

Debugging U-boot is very similar to debugging the Preloader. The same techniques are available.

The Preloader Support Package Generator creates the file uboot.ds in the Preloader folder, that can be used to debug the U-Boot from the ARM DS-5 AE. Since the executable is an ELF format, any other compatible debugger may be used, as well.

Boot Examples

This chapter presents several boot examples that can be run on the Cyclone V Development Kit:

Boot from SD/MMC - using raw and FAT partitions
Boot from QSPI
Boot from FPGA

In all the examples, the Preloader is used to load and run a simple bare-metal application. The boot flow is depicted in the following figure:

Figure 8. Boot Flow

Archive File Contents

This document has an accompanying archive file with all the source code required to reproduce the examples from this chapter, and also all the binaries required to run the examples without building them.

The archive is called cv_boot_guide.zip and contains the following:

prebuilt
- application
  - hello-mkimage.bin
- fpga
  - soc_system.sof
- preloaders
  - sd_custom_partition
    - preloader-mkpimage.bin
  - sd_fat_partition
    - preloader-mkpimage.bin
  - qspi
    - preloader-mkpimage.bin
  - fpga
    - preloader-mkpimage.bin
sources
- cv_soc_devkit_boot_fpga_rd
- Altera-SoCFPGA-HardwareLib-Unhosted-CV-GNU.tar.gz

Bare-Metal Application

The bare-metal application used in all the examples simply displays the Hello World message over UART.

The application is included as an importable project called Altera-SoCFPGA-HardwareLib-Unhosted-CV-GNU.tar.gz. It can also be downloaded from the SoC Example Designs webpage.

Import the project archive in ARM DS-5 AE and build it. This will create the file hello-mkimage.bin, which is the image that will be loaded by the Preloader.

Booting from SD/MMC – Custom Partition

This example demonstrates how to boot from the SD card, with the bare-metal image stored on the same SD card custom partition as the Preloader.

To prevent the "Device Open Failed!" error message, ensure that you are operating in the following user modes:

Windows — "Administrator mode user"
Linux — "sudo mode"

The steps required to run this scenario are:

Build the sample bare-metal application or simply use the provided file hello-mkimage.bin directly.
Generate a Preloader based on the GHRD provided with SoC EDS.
Make sure to select the following options:
- Check the option spl.boot.BOOT_FROM_SDMMC
- Uncheck the other boot options (spl.boot.BOOT_FROM_RAM, spl.boot.BOOT_FROM_QSPI, spl.boot.BOOT_FROM_NAND)
  Note: spl.boot.SDMMC_NEXT_BOOT_IMAGE = 0x40000. This is the location where the bare-metal application image will need to be stored.
- Check the option spl.boot.SDRAM_SCRUBBING and spl.boot.SDRAM_SCRUB_REMAIN_REGION. This will zero out the SDRAM, preventing any ECC errors to occur during bare-metal program execution.
- Uncheck the option spl.boot.WATCHDOG_ENABLE. This is because we are not kicking the watchdog in our bare-metal application.
Compile the Preloader. This will create the file preloader-mkpimage.bin.
Manually create an SD card with a custom partition with id=A2 using fdisk, or use the example SD card image that comes with SoC EDS:
- Unzip the SD Card Image provided in the <SoCEDS installation folder>:\embedded\embeddedsw\socfpga\prebuilt_images\sd_card_linux_boot_image.tar.gz by using the command ‘tar -xzf <filename>’ from the Embedded Command Shell. This will create the file sd_card_linux_boot_image.img.
- Use the free Win32DiskImager tool to write the file sd_card_linux_boot_image.img to an SD card.
Write only the Preloader image to the SD card custom partition, using the SD card boot utility that is part of SoC EDS:
- Start an Embedded Command Shell.
- Run the command “alt-boot-disk-util -a write -p preloader-mkpimage.bin -b hello-mkimage.bin -d <sd_card_drive_letter>”
Set the board to boot from SD card by configuring the BOOTSEL jumpers like this:
- BOOTSEL0 (J28): left
- BOOTSEL1 (J29): right
- BOOTSEL2 (J30): left
Connect the board to the PC using the USB serial connection, and start a serial terminal on the PC, using 115,200-8-N-1.
Insert the SD card on the board socket and power-cycle the board or reset the HPS by pressing the COLD reset button (S7).

The board will boot, Preloader messages will be displayed, then “Hello World” will be displayed by the bare-metal application.
Figure 9. Custom Partition

Booting from SD/MMC – FAT Partition

This example demonstrates how to boot from the SD card, with the bare-metal image stored on the FAT partition on the SD card.

Note: The Preloader is still stored on the custom partition.

To prevent the "Device Open Failed!" error message, ensure that you are operating in the following user modes:

Windows — "Administrator mode user"
Linux — "sudo mode"

The steps required to run this scenario are:

Build the sample bare-metal application or simply use the provided file hello-mkimage.bin directly.
Generate a Preloader based on the GHRD provided with SoC EDS. Make sure to select the following options:
- Check the option spl.boot.BOOT_FROM_SDMMC
- Uncheck the other boot options (spl.boot.BOOT_FROM_RAM, spl.boot.BOOT_FROM_QSPI, spl.boot.BOOT_FROM_NAND)
- Check the option spl.boot.FAT_SUPPORT. This will tell the Preloader to load the bare-metal application from the FAT partition.
- Edit the field spl.boot.FAT_LOAD_PAYLOAD_NAME to contain the name of the bare-metal image: hello-mkimage.bin
- Check the option spl.boot.SDRAM_SCRUBBING and spl.boot.SDRAM_SCRUB_REMAIN_REGION. This will zero out the SDRAM, preventing any ECC errors to occur during bare-metal program execution.
- Uncheck the option spl.boot.WATCHDOG_ENABLE. This is because we are not kicking the watchdog in our bare-metal application.
Compile the Preloader. This will create the file preloader-mkpimage.bin.
Manually create an SD card with a custom partition with id=A2 using fdisk, or use the example SD card image that comes with SoC EDS:
- Unzip the SD Card Image provided in the <SoCEDS installation folder>:\embedded\embeddedsw\socfpga\prebuilt_images\sd_card_linux_boot_image.tar.gz by using the command ‘tar -xzf <filename>’ from the Embedded Command Shell. This will create the file sd_card_linux_boot_image.img.
- Use the free Win32DiskImager tool to write the file sd_card_linux_boot_image.img to an SD card.
Write both the Preloader image and the Bare-metal application images to the SD card custom partition, using the SD card boot utility that is part of SoC EDS:
- Start an Embedded Command Shell.
- Run the command “alt-boot-disk-util -a write -p preloader-mkpimage.bin -d <sd_card_drive_letter”
Write the bare-metal application image to the SD card FAT partition, using for example drag and drop in Windows Explorer.
Set the board to boot from SD card by configuring the BOOTSEL jumpers like this:
- BOOTSEL0 (J28): left
- BOOTSEL1 (J29): right
- BOOTSEL2 (J30): left
Connect the board to the PC using the USB serial connection, and start a serial terminal on the PC, using 115,200-8-N-1.
Insert the SD card on the board socket and power-cycle the board or reset the HPS by pressing the COLD reset button (S7).

The board will boot, Preloader messages will be displayed, then “Hello World” will be displayed by the bare-metal application.
Figure 10. FAT Partition

Booting from QSPI Flash

This example demonstrates how to boot from the QSPI Flash. Both the Preloader and the Bare-metal application are stored in QSPI Flash.

The steps required to run this scenario are:

Build the sample bare-metal application or simply use the provided file hello-mkimage.bin directly.
Generate a Preloader based on the GHRD provided with SoC EDS. Make sure to select the following options:
- Check the option spl.boot.BOOT_FROM_QSPI
- Uncheck the other boot options (spl.boot.BOOT_FROM_RAM, spl.boot.BOOT_FROM_SDMMC, spl.boot.BOOT_FROM_NAND)
  Note: spl.boot.QSPI_NEXT_BOOT_IMAGE = 0x60000. This is the location where the bare-metal application image will need to be stored.
- Check the option spl.boot.SDRAM_SCRUBBING and spl.boot.SDRAM_SCRUB_REMAIN_REGION. This will zero out the SDRAM, preventing any ECC errors to occur during bare-metal program execution.
- Uncheck the option spl.boot.WATCHDOG_ENABLE. This is because we are not kicking the watchdog in our bare-metal application.
Compile the Preloader. This will create the file preloader-mkpimage.bin.
Set the board to boot from SD card by configuring the BOOTSEL jumpers like this:
- BOOTSEL0 (J28): left
- BOOTSEL1 (J29): left
- BOOTSEL2 (J30): left
Connect the USB Blaster USB cable from board to the host PC. This is needed by the HPS Flash Programmer used in the next step.
Write the Preloader and the application images to the QSPI Flash by starting an Embedded Command Shell and then running the following commands:
- quartus_hps -c 1 -o PV preloader-mkpimage.bin
- quartus_hps -c 1 -o PV -a 0x60000 hello-mkimage.bin
Power-cycle the board or reset the HPS by pressing the COLD reset button (S7).

The board will boot, Preloader messages will be displayed, then “Hello World” will be displayed by the bare-metal application.
Figure 11. Booting from QSPI Flash

Booting from FPGA

This section presents a complete example on how to boot from FPGA.

When instructed to boot from FPGA, the Boot ROM performs the following operations:

Waits for the FPGA fabric to be configured
Waits for FPGA to be in user mode
Opens the HPS-to-FPGA bridge
Jumps to address 0xC0000000 (offset 0 from the HPS-to-FPGA bridge)

Overview

In this example, we have the Preloader running from FPGA, but then it will load the bare-metal image that we have on SD/MMC custom partition. If desired, the Preloader can also be configured to jump to an absolute address, that may also be located in the FPGA fabric address space.

The boot flow of this example is described below:

Figure 12. Boot Flow

In order to achieve booting from FPGA the following are required:

BSEL needs to be set to 0x1 - Boot from FPGA
FPGA image needs to have an on-chip memory instantiated, mapped at offset 0x0 behind the HPS2FPGA bridge. The memory needs to be loaded with Preloader executable binary
FPGA image needs to drive the value of the following two signals to HPS, since they are required by Boot ROM:
- f2h_boot_from_fpga_ready - indicates that the Boot ROM can boot from FPGA if BSEL = 0x1
- f2h_boot_from_fpga_on_failure - indicates that the Boot ROM can boot from FPGA as a fallback, if it failed booting from the selected BSEL
Preloader executable (.text) section needs to be linked to address 0xC0000000 (equivalent of offset 0x0 behind the HPS2FPGA bridge)
Preloader executable (.data) sections need to be linked to address 0xFFFF0000 (the HPS OCRAM)

The complete flow is described in the following figure:

Figure 13. Complete Flow

Note: The design needs to be compiled once in order to obtain the handoff folder, which is used to generate the Preloader. Once the Preloader hex file is obtained, the design is compiled again in order to have the FPGA memory initialized with the contents of the hex file.

Hardware Design

This section presents a very simple hardware design that was used for this example. You will need ACDS to be installed on your host PC to be able to reproduce this example.

Note: The design is already provided with this guide. It does not need to be re-created by the user. But it will need to be re-compiled if the Preloader hex file is changed.

The design is based on the Altera GHRD, with a reduced number of components:

HPS - Hard Processor Instance
SysID - System ID
HPS Boot Memory - FPGA memory used to store Preloader binary
Clk - Clock and Reset source

The following picture presents the System Contents view for the hardware design:

Figure 14. System Contents View for the Hardware Design

The HPS Component needs to be configured to enable the Boot from FPGA signals as shown in the screenshot below:

Figure 15. Enable Boot From FPGA Signals

The HPS Boot Memory needs to be set to 8-bit width, and be initialized with a hex file containing the Preloader image. The following screenshot show the memory settings that were used for this example.

Note: The Preloader image is stored in the file named software/spl_bsp/preloader.hex.

Figure 16. On-Chip Memory Parameters

Note:

The HPS bus f2h_boot_from_fpga was exported by double-clicking the corresponding cell in the Export column.
The HPS Boot Memory was connected to the h2f AXI bus.
The HPS Boot Memory was set to a base address of 0x0000000.

The f2h_boot_from_fpga signals need to be tied at the top level to the proper values. For this example, they were tied like this in the file rd_top.v:

// SoC sub-system module
soc_system soc_inst (  ... 
        .hps_0_f2h_boot_from_fpga_boot_from_fpga_ready         (1'b1), 
        .hps_0_f2h_boot_from_fpga_boot_from_fpga_on_failure    (1'b0));

Building and Running the Example

This section presents the steps required in order to build and run the boot from FPGA example.

Note: All the binaries are also provided with the archive file that accompanies this document.

To prevent the "Device Open Failed!" error message, ensure that you are operating in the following user modes:

Windows — "Administrator mode user"
Linux — "sudo mode"

Build the sample bare-metal application or simply use the provided file hello-mkimage.bin directly.
Compile the provided Booting from FPGHA Hardware Design in Intel^® Quartus^® Prime, to create the handoff information.
Generate the Preloader based on the compiled hardware project. Select the following options:
- Check the option spl.boot.BOOT_FROM_SDMMC
- Uncheck the other boot options (spl.boot.BOOT_FROM_RAM, spl.boot.BOOT_FROM_QSPI, spl.boot.BOOT_FROM_NAND)
- Uncheck the option spl.boot.FAT_SUPPORT. This will tell the Preloader to load the bare-metal application from the custom partition.
  Note: spl.boot.SDMMC_NEXT_BOOT_IMAGE = 0x40000. This is the location where the bare-metal application image will need to be stored.
- Check the option spl.boot.SDRAM_SCRUBBING and spl.boot.SDRAM_SCRUB_REMAIN_REGION. This will zero out the SDRAM, preventing any ECC errors to occur during bare-metal program execution.
- Uncheck the option spl.boot.WATCHDOG_ENABLE. This is because we are not kicking the watchdog in our bare-metal application.
- Check the option spl.boot.EXE_ON_FPGA.
Compile the Preloader. This will create the Preloader executable.
Convert the Preloader executable to hex file by using the following command in the Preloader folder: arm-altera-eabi-objcopy -O ihex --adjust-vma -0xc0000000 uboot-socfpga/spl/u-boot-spl preloader.hex
Compile the hardware design again, to take into account the newly created hex file.

Note: The hex file is expected to be located in the <hardware_design_folder>/software/spl_bsp/preloader.hex. This will create the file <hardware_design_folder>/output_files/soc_system.sof.
Manually create an SD card with a custom partition with id=A2 using fdisk, or use the example SD card image that comes with SoC EDS:
- Unzip the SD Card Image provided in the <SoCEDS installation folder>:\embedded\embeddedsw\socfpga\prebuilt_images\sd_card_linux_boot_image.tar.gz by using the command ‘tar -xzf <filename>’ from the Embedded Command Shell. This will create the file sd_card_linux_boot_image.img.
- Use the free Win32DiskImager tool to write the file sd_card_linux_boot_image.img to an SD card.
Write the Bare-metal application image to the SD card custom partition, using the SD card boot utility that is part of SoC EDS:
- Start an Embedded Command Shell
- Run the command “alt-boot-disk-util -a write -b hello-mkimage.bin -d <sd_card_drive_letter>”
Configure the Cyclone V board to boot from FPGA by setting the BOOTSEL jumpers like this:
- BOOTSEL0 (J28): left
- BOOTSEL1 (J29): right
- BOOTSEL2 (J30): right
Connect the board to the PC using the USB serial connection, and start a serial terminal on the PC, using 115,200-8-N-1.
Insert the SD card on the board.
Power up the board.
There should be nothing coming from the board on the serial terminal, since the FPGA is not configured, so the Boot ROM will not jump to FPGA yet.
Configure the FPGA by using the Intel^® Quartus^® Prime Programmer, with the (.sof) file.

Note: The (.sof) file is already included in the archive that accompanies this document.
Press the HPS Cold Reset button (S7).
The serial console will show the Preloader being run from FPGA, then the bare-metal application being run from the SD card.

Figure 17. Serial Console of Preloader Running from FPGA

Document Revision History

Table 9. Document Revision History
Date	Version	Changes
January 2016	2016.01.27	Added note to remind user to be in administrator or sudo mode when using `alt-boot-disk-util`.
April 2015	2015.04.27	Updated the SD card boot utility command Fixed incorrect spelling of "BootROM" in figures
March 2015	2015.03.26	Fixed broken links.
December 2014	2014.12.15	Added information for Boot Time Optimization and Boot Debug.