eMMC ABR behavior

eMMC ABR behavior

[Joel Stanley]

Hello Ryan,

We are testing eMMC ABR by corrupting the u-boot image. When the eMMC
ABR mode kicks in, we then boot as expected from the boot1 image. We
then restore the working boot0 image, and reboot the system, which
still boots into boot1. In order to boot from boot0 again we must
power cycle the system.

I see two scenarios:

1. This is expected. The BMC software is expected to recognise that
the ABR mode switch has occurred, and based on policy, configure the
ABR to go back to boot0 or raise an error.

2. This is unexpected. The BMC should always try that boot0 image on
each boot, from both a software reset or a power on reset. We should
add code to the kernel watchdog driver to ensure the ABR mode is reset
before system reboots.

Cheers,

Joel

RE: eMMC ABR behavior

[Chin-Ting Kuo]

Hi Joel,

If you want to trigger WDT SoC reset, namely, warm reboot, and boot from boot0 partition, SECA0[4] should be cleared by writing 0xEA to SECA0[23:16].
Remember to unlock sec register by controlling SEC00 register.



Thanks.

Best Wishes,
Chin-Ting

> -----Original Message-----
> From: Joel Stanley <joel@jms.id.au>
> Sent: Wednesday, May 25, 2022 8:51 AM
> To: Ryan Chen <ryan_chen@aspeedtech.com>
> Cc: OpenBMC Maillist <openbmc@lists.ozlabs.org>
> Subject: eMMC ABR behavior
> 
> Hello Ryan,
> 
> We are testing eMMC ABR by corrupting the u-boot image. When the eMMC
> ABR mode kicks in, we then boot as expected from the boot1 image. We then
> restore the working boot0 image, and reboot the system, which still boots into
> boot1. In order to boot from boot0 again we must power cycle the system.
> 
> I see two scenarios:
> 
> 1. This is expected. The BMC software is expected to recognise that the ABR
> mode switch has occurred, and based on policy, configure the ABR to go back
> to boot0 or raise an error.
> 
> 2. This is unexpected. The BMC should always try that boot0 image on each
> boot, from both a software reset or a power on reset. We should add code to
> the kernel watchdog driver to ensure the ABR mode is reset before system
> reboots.
> 
> Cheers,
> 
> Joel