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Re: [Qemu-devel] [PATCH 06/10] r2d: Flash memory creation is confused ab

From: Markus Armbruster
Subject: Re: [Qemu-devel] [PATCH 06/10] r2d: Flash memory creation is confused about size, mark FIXME
Date: Tue, 19 Feb 2019 16:45:47 +0100
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux)

Peter Maydell <address@hidden> writes:

> On Mon, 18 Feb 2019 at 13:07, Markus Armbruster <address@hidden> wrote:
>> pflash_cfi02_register() takes a size in bytes, a block size in bytes
>> and a number of blocks.  r2d_init() passes FLASH_SIZE, 16 * KiB,
>> FLASH_SIZE >> 16.  Does not compute: size doesn't match block size *
>> number of blocks.  The latter happens to win.  I tried to find
>> documentation on the physcial hardware, no luck.
>> For now, adjust the byte size passed to match the actual size created,
>> and add a FIXME comment.
> I'm pretty sure that FLASH_SIZE here is supposed to be a
> byte count of the size of the pflash. That matches what
> Linux has in arch/sh/boards/mach-r2d/setup.c where it
> sets up the flash_resource struct.

Okay, that's some evidence for size 0x02000000 (32MiB).

However, we've created size (16 * KiB) * (FLASH_SIZE >> 16), i.e. 8MiB,
since at least commit 368a354f02b (v1.3.0), possibly since forever.

> The r2dplus board is also I think known as RTS7751R2D. That
> takes us to https://elinux.org/RTS7751R2D_Handling_Manual
> (sadly the link to the "hardware manual" is broken).

Quote section Flash ROM Mapping:

    Currently, MTD device mapping on Flash ROM is set as below.
    0x00000000-0x00020000       "bootloader"    
    0x00020000-0x00320000       "mtdblock1"     XIP kernel
    0x00320000-0x00520000       "mtdblock2"     
    0x00520000-0x01000000       "mtdblock3"     

Suggests a size of 0x01000000 (16MiB).  Now we have three candidates.

Pick one, any one, and I'll adjust my patch.  All I really care about is
getting argument @size consistent with arguments @sector_len and
@nb_blocs, so I can ditch @nb_blocs in PATCH 09.

> No idea what the block size would be.

As long as that's the case, inertia wins by default.

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