Re: [Qemu-devel] [PATCH 06/10] r2d: Flash memory creation is confused about size, mark FIXME

[Markus Armbruster <armbru@redhat.com>]

Magnus Damm <magnus.damm@gmail.com> writes:

> Hi guys,
>
> On Wed, Feb 20, 2019 at 2:31 AM Markus Armbruster <armbru@redhat.com> wrote:
>>
>> Philippe Mathieu-Daudé <philmd@redhat.com> writes:
>>
>> > On 2/19/19 4:45 PM, Markus Armbruster wrote:
>> >> Peter Maydell <peter.maydell@linaro.org> writes:
>> >>
>> >>> On Mon, 18 Feb 2019 at 13:07, Markus Armbruster <armbru@redhat.com> 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.
>> >
>> > "physical"
>>
>> Thanks, will fix.
>>
>> >>>>
>> >>>> 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)
>>
>> Candidate #4: 64MiB.  Bring 'em on!
>>
>> >
>> > 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
>>
>> That's a vote for changing the status quo (8 MiB).
>>
>> Perhaps Magnus, who maintains the machine, can pick a new value for us.
>
> According to the old board user document in Japanese (under NDA) what
> is referred to as FROM (Area0) is connected via a 32-bit bus and CS0
> to CN8. The docs mention s29pl127j60tfi130 but since I don't have the
> board handy ATM I don't know how the chips are connected.
>
> Hope this helps,

If you want me to change our emulated flash memory's size, please give
me a number.