Cold boot consistently fails to load file from SD

[Daniel Schwierzeck]

Hi Mauro,

Am Samstag, den 19.09.2020, 15:39 +0200 schrieb Mauro Condarelli:

> Hi,
> I'm facing a new problem for my Mt7628/vocore2 target.
> 
> I moved the Linux kernel from a ext4 partition to the "proper" SquashFS partition (I say "proper" because I'm using a dual-system with fallback to avoid updating the currently working rootFS and kernel lies into rootFS).
> 
> I am using u-boot v2020.10-rc3 plus the attached patches (one pertains SquashFS).
> 
> Problem is a real cold boot (target off for more than one minute) leads to a load failure for the kernel. A warm boot ("reboot" from a running Linux) or a not-so-cold boot (turn target off and power it on again after a few seconds) seems to work as expected.

which distro or Linux version do you use? Can you provide a full boot
log?

Linux MIPS had a bug with setting up memory for its exception vectors
and handlers if the CPU didn't report support for vectored interrupts.
mtmips is one of those CPUs. AFAIK this should have been fixed in
mainline since some months. Could be one reason. 

You could also try to disable CONFIG_RESTORE_EXCEPTION_VECTOR_BASE in
U-Boot. 

Stefan also had cache issues on the Gardena board. He solved it with
some memory allocation and copying, see arch/mips/mach-mtmips/cpu.c.

The cmd_cache interface is not supported on MIPS as there is no
reliable way to disable or enable caches or to separately control i-
cache and d-cache.

Can you send patches 0001 and 0002 to the mailing list in the proper
way so that patchwork can pick them up? I'd like to prepare a small
bugfix pull request for v2020.10. Thanks.

-- 
- Daniel