[PATCH 1/2] arm: mach-k3: common: Make sure firmware sections are loaded prior to armv8 startup

Tom Rini trini at konsulko.com
Sat Sep 18 00:53:23 CEST 2021


On Tue, Aug 31, 2021 at 01:20:48PM -0500, Nishanth Menon wrote:

> With Device Manager firmware in an elf file form, we cannot load the FIT
> image to the exact same address as any of the executable sections of the
> elf file itself is located.
> 
> However, the device tree descriptions for the ARMV8 bootloader/OS
> includes DDR regions only the final sections in DDR where the Device
> Manager firmware is actually executing out of.
> 
> As the R5 uC is usually operating at a slower rate than an ARMv8 MPU,
> by starting the Armv8 ahead of parsing the elf and copying the correct
> sections to the required memories creates a race condition where the
> ARMv8 could overwrite the elf image loaded from the FIT image prior to
> the R5 completing parsing and putting the correct sections of elf in
> the required memory locations. OR create rather obscure debug conditions
> where data in the section is being modified by ARMV8 OS while the elf
> copy is in progress.
> 
> To prevent all these conditions, lets make sure that the elf parse and
> copy operations are completed ahead of ARMv8 being released to execute.
> 
> We will pay a penalty of elf copy time, but that is a valid tradeoff in
> comparison to debug of alternate scenarios.
> 
> Signed-off-by: Nishanth Menon <nm at ti.com>

Applied to u-boot/master, thanks!

-- 
Tom
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