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Re: [Qemu-block] [Qemu-devel] [PATCH v2 07/11] ppc405_boards: Don't size
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH v2 07/11] ppc405_boards: Don't size flash memory to match backing image |
Date: |
Thu, 07 Mar 2019 08:01:35 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) |
Alex Bennée <address@hidden> writes:
> Markus Armbruster <address@hidden> writes:
>
>> Machine "ref405ep" maps its flash memory at address 2^32 - image size.
>> Image size is rounded up to the next multiple of 64KiB. Useless,
>> because pflash_cfi02_realize() fails with "failed to read the initial
>> flash content" unless the rounding is a no-op.
>>
>> If the image size exceeds 0x80000 Bytes, we overlap first SRAM, then
>> other stuff. No idea how that would play out, but a useful outcomes
>> seem unlikely.
>>
>> Map the flash memory at fixed address 0xFFF80000 with size 512KiB,
>> regardless of image size, to match the physical hardware.
>>
>> Machine "taihu" maps its boot flash memory similarly. The code even
>> has a comment /* XXX: should check that size is 2MB */, followed by
>> disabled code to adjust the size to 2MiB regardless of image size.
>>
>> Its code to map its application flash memory looks the same, except
>> there the XXX comment asks for 32MiB, and the code to adjust the size
>> isn't disabled. Note that pflash_cfi02_realize() fails with "failed
>> to read the initial flash content" for images smaller than 32MiB.
>>
>> Map the boot flash memory at fixed address 0xFFE00000 with size 2MiB,
>> to match the physical hardware. Delete dead code from application
>> flash mapping, and simplify some.
>
> It seems to me the DEBUG_BOARD_INIT code is probably out of date cruft
> that could be excised all together. But that doesn't stop this being
> useful:
David, would you like me to excise DEBUG_BOARD_INIT?
> Reviewed-by: Alex Bennée <address@hidden>
Thanks!