Subject: Re: [PATCH] cpu: imx8_cpu: Avoid revision to corrupt device tree
On Thu, Oct 17, 2024 at 01:10:02AM +0000, Peng Fan wrote:
Subject: Re: [PATCH] cpu: imx8_cpu: Avoid revision to corrupt
device
tree
On Sat, Oct 12, 2024 at 12:16:14AM +0000, Peng Fan wrote:
Subject: Re: [PATCH] cpu: imx8_cpu: Avoid revision to corrupt
device
tree
Why isn't this padding and alignment with the BSS being
taken
care
of
in either the linker script or the binman dts?
Sorry, I am not sure what you mean.
I mean, why are things placed in this position to start with? Why is the device tree not already in a place where we aren't smashing it at run time? Is this a problem of the alignment / placement of items
in a blob?
A runtime placement problem? What?
Whether binman or not. I think u-boot.dtb is padded just end of u-boot-nodtb.bin. Not alignment or else.
This is a common issue, bss should not be written before reloc_fdt.
It's possible I'm missing the examples in my quick grep right now but, yes, why are you needing to make this device tree change so early? We should not be using the "put this in the data section" kludge unless strictly necessary. Why is this necessary and cannot wait until, well, further along in the boot? This is supposed to be for pre-DRAM- initialization stuff.
You may misunderstand. It is imx8_cpu driver probe at pre reloc stage before reloc_fdt, so the written to bss area in imx8_cpu driver will corrupt device tree which padded after u-boot-nodtb.bin.
Then after reloc_fdt, the new dtb is actually a broken one.
Regards, Peng.
-- Tom