On Sat, Jul 9, 2016 at 9:42 AM, Alexey Brodkin Alexey.Brodkin@synopsys.com wrote:
Recently I started to notice that u-boot.img built for Wandboard by some toolchains becomes so large that it basically overlaps with U-Boot environment area on SD-card.
According to http://wiki.wandboard.org/index.php/Boot-process#sdcard_boot_data_layout Wandboard's SD-card layout is as follows:
------------------------------>8---------------------------
- 0x00000000 Reserved For MBR
- 0x00000200 512 Secondary Image Table (optional)
- 0x00000400 1024 uBoot Image (Starting From IVT)
- 0x00060000 393216 start of uboot env (size:8k)
- 0x00062000 end of uboot env
- 0x00100000 1048576 Linux kernel start
- 0x0076AC00 7777280 start of partition 1
------------------------------>8---------------------------
So for U-Boot we have 383kB (392192 bytes).
But in up to date U-Boot for Wandboard we build separately a) SPL b) u-boot.img
which gives us a bit more detailed SD-card layout:
------------------------------>8---------------------------
- 0x00000000 Reserved For MBR
- 0x00000200 512 Secondary Image Table (optional)
- 0x00000400 1024 SPL
- 0x00011400 70656 u-boot.img
- 0x00060000 393216 start of uboot env (size:8k)
- 0x00062000 end of uboot env
... ------------------------------>8---------------------------
From that layout we may calculate amount of space reserved for u-boot.img. It's just 315kb (322560 bytes).
Now if I build U-Boot with Sourcery CodeBench ARM 2014.05 produced u-boot.img is already more than we expected (323840 bytes instead of "< 322560"): ------------------------------>8--------------------------- ls -la u-boot.img -rw-rw-r-- 1 user user 323840 Jul 5 07:38 u-boot.img ------------------------------>8---------------------------
Funny enough if I rebuild U-Boot with ARM toolchain available in my Fedora 23 distro u-boot.img becomes a little bit smaller: ------------------------------>8--------------------------- ls -la u-boot.img -rw-rw-r-- 1 user user 322216 Jul 5 07:39 u-boot.img ------------------------------>8---------------------------
What's worse this problem might not affect people most of the time because what happens people would just copy u-boot.img on SD-card and live in happiness with it... well until somebody attempts to save environment in U-Boot with "saveenv" command which will simply overwrite the very end of u-boot.img. That will lead to unusable SD-card until user dd u-boot.img on SD-card again.
I may foresee this issue in the future to become more visible once we add more features in U-Boot for Wandboard or just existing code base becomes bulkier and people will consistently get larger u-boot.img files produced.
IMHO there's an obvious solution for all that - just move U-Boot's env to the very end of the gap between U-Boot and the first real partition on the SD-card. This patch will follow 8fb9eea5653796 ("mx6sabre_common: Fix U-Boot corruption after 'saveenv'"). So env is still not in the very end of the gap (obviously 256kb is way too much for U-Boot's env) but at least we have now the same partitioning for i.MX6 boards.
Signed-off-by: Alexey Brodkin abrodkin@synopsys.com Cc: Fabio Estevam fabio.estevam@nxp.com Cc: Otavio Salvador otavio@ossystems.com.br Cc: Peter Robinson pbrobinson@gmail.com Cc: Tom Rini trini@konsulko.com Cc: Peter Korsgaard peter@korsgaard.com Cc: Wolfgang Denk wd@denx.de
Couldn't this be done on the common header?