View source for How to update U-Boot on an SD card

This page explains how to manually update the [[U-Boot_overview|U-Boot]] binaries on an SD card.

== Copying a binary to an SD card with the Linux dd command ==

When you have access to the device (with the card reader of a PC, or the [[How to use USB mass storage in U-Boot|<code>ums</code> command]] on a target), [[STM32MP15_Flash_mapping#SD_card_memory_mapping|the 3 first partitions on the SD card]] are:
# FSBL1
# FSBL2
# SSBL

See [[Boot_chains_overview]] for the bootloader definitions.

You can use the Linux <code>dd</code> command to copy the FSBL and SSBL directly to the correct partition:

  {{PC$}}  dd if=<file> of=/dev/<dev> conv=fdatasync

<dev> is:
* mmcblk<X>p<n> : PC-embedded card reader case
* sd<X><N> : USB-connected SD card reader case
where <X> is the ID of the device, and <n> the ID of the partition.

Note: the dd option conv=fdatasync is used to force synchronous copying.

== Trusted boot chain update example ==
The internal card reader is /dev/mmcblk0, partition <n> is /dev/mmcblk0p<n>:

  {{PC$}} dd if=tf-a.stm32 of=/dev/mmcblk0p1 conv=fdatasync
  {{PC$}} dd if=tf-a.stm32 of=/dev/mmcblk0p2 conv=fdatasync
  {{PC$}} dd if=u-boot.stm32 of=/dev/mmcblk0p3 conv=fdatasync

== Basic boot chain udpate example ==
The USB card reader is /dev/sdb, partition <n> is /dev/sdb<n>

  {{PC$}} dd if=u-boot-spl.stm32 of=/dev/sdb1 conv=fdatasync
  {{PC$}} dd if=u-boot-spl.stm32 of=/dev/sdb2 conv=fdatasync
  {{PC$}} dd if=u-boot.img of=/dev/sdb3 conv=fdatasync

== update of eMMC ==

The same command, <code>dd</code>, can be used to update eMMC with [[How to use USB mass storage in U-Boot|<code>ums</code> command]], but the SSBL = TF-A (or SPL) can't be saved directly in the cached boot partitions, and the indexes of other partitions need to be adapted.
 
For the user area, we use GPT partitioning. SSBL is the first user partition in [[STM32MP15_Flash_mapping#eMMC_memory_mapping|eMMC memory mapping]] :

  {{Board$}} ums 0 mmc 1
  {{PC$}} dd if=u-boot.stm32 of=/dev/sdb1 conv=fdatasync

For the boot partition, the user needs to select the targeted partition with the third parameter {{HighlightParam|partition_access}} of command <code>{{Highlight|mmc partconf}}</code> :
* {{HighlightParam|0}}: user data partition
* {{HighlightParam|1}}: boot partition 1
* {{HighlightParam|2}}: boot partition 2

  {{Board$}}  help mmc 
  ...
  mmc bootbus dev boot_bus_width reset_boot_bus_width boot_mode
 - Set the BOOT_BUS_WIDTH field of the specified device
  mmc bootpart-resize <dev> <boot part size MB> <RPMB part size MB>
 - Change sizes of boot and RPMB partitions of specified device
  mmc partconf dev [boot_ack boot_partition {{HighlightParam|partition_access}}]
 - Show or change the bits of the PARTITION_CONFIG field of the specified device
  ..
  
For example, 
* dev = 1 (eMMC device on ST Microelectronics board)
* boot_ack=1 (Boot Acknowledge is needed by ROM code) 
* boot_partition = 1 (Boot partition 1 enabled for boot)
* {{HighlightParam|partition_access}} =  {{HighlightParam|0}} (No access to boot partition - default) 
* or {{HighlightParam|partition_access}} =  {{HighlightParam|1}} (R/W boot partition 1) 

To copy FSBL with a <code>ums</code> command and come back to the user area, we have:
  {{Board$}} mmc dev 1
  {{Board$}} mmc partconf 1 1 1 {{HighlightParam|1}}
  {{Board$}} ums 0 mmc 1
  {{PC$}} dd if=tf-a.stm32 of=/dev/mmcblk0p1 conv=fdatasync
  {{Board$}} mmc partconf 1 1 1 {{HighlightParam|0}}

<noinclude>
[[Category:How to populate boards]]
{{PublicationRequestId | 13227 | 2019-09-11}}
</noinclude>