hw/arm/aspeed:Added mmc boot support for AST2600 eMMC image.

[shitalkumar-gandhi]

This patch has been added to boot eMMC image for AST2600 machine on
QEMU.

Run quemu as follows:

./qemu-system-arm -m 1G -M ast2600-evb -nographic -drive
file=mmc-evb-ast2600.img,format=raw,if=sd,index=2

Tested: Booted AST2600 eMMC image on QEMU.
Signed-off-by: Shitalkumar Gandhi [email protected]

[shitalkumar-gandhi]

@williamspatrick @amboar @legoater @shenki please review.

[amboar]

Hi @shitalkumar-gandhi , thanks for the patch. For qemu we try to do upstream first and only accept downstream patches if it's truly necessary (usually outright hacks that have an unfortunate bang-for-buck value).

That said you should review the conversation here on this exact topic: openbmc/openbmc#3818 . It's hard to say how the ast2600 evb boot configuration should be managed, and worse, because of the situation upstream with eMMC it's hard to see an way forward that isn't a minefield. Anyway, if you have some thoughts after reading the linked thread I'm interested to hear them :)

[legoater]

@shitalkumar-gandhi, yes, the QEMU patches should be sent upstream on the qemu-devel mailing list and this patch is changing a default behavior :/ I think the right approach would be to use the boot index of the device on the command line.

Could you please check an alternate and easier approach in https://github.com/legoater/qemu/commits/aspeed-6.2 ? The changes add a boot-emmc machine option to set/unset the emmc boot.

To boot from emmc on the ast2600-evb QEMU machine, you will need to use option -M ast2600-evb,boot-emmc=true

@amboar @shenki Could you give it a try ? Thanks.

[shitalkumar-gandhi]

Hi @legoater

The following option is not working in QEMU for eMMC boot.
-M ast2600-evb,boot-emmc=true

Hi @amboar

I don't have the alternate approach. I feel this change should be included in QEMU's upstream.

Please let me know what you think about this.
Thanks to all for the responses.

[amboar]

@shitalkumar-gandhi this change won't be acceptable upstream as is because it prevents booting from SPI-NOR (by forcing the boot source to eMMC). Either boot source is valid for the EVB, so we need a solution that allows for both.

[legoater]

@shitalkumar-gandhi which QEMU repository and which branch are you using ?

[shitalkumar-gandhi]

ok @amboar thanks got it, we should have a mechanism that permits both eMMC and flash booting.
@legoater I am using your repo i.e. https://github.com/legoater/qemu and aspeed-6.2 branch.

[legoater]

Could you please give us the command line, the reported errors and access to the eMMC image you are using. Thanks