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

From: Philippe Mathieu-Daudé
Subject: Re: [Qemu-devel] [PATCH 06/10] r2d: Flash memory creation is confused about size, mark FIXME
Date: Tue, 19 Feb 2019 16:53:04 +0100
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0

On 2/19/19 4:45 PM, Markus Armbruster wrote:
> 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.

There is also a paper [*]:

  The Renesas Technology R0P751RLC001RL (R2DPLUS) board was used
  as our target device.
  This board is often used to evaluate software for CE devices.
  The specification is shown below.
    CPU: SH7751R(SH4) 240Mhz
    RAM: 64Mbyte
    Compact flash: 512Mbyte
    Flash ROM: 64Mbyte (32Mbyte available for root file system)

Let's use at least 16MB to be able to run the elinux cited kernel.

[*] https://www.kernel.org/doc/ols/2008/ols2008v2-pages-125-134.pdf

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