Re: [PATCH v45 3/3] hw/sd/sdcard: Do not store vendor data on block drive (CMD56)

[Philippe Mathieu-Daudé]

On 3/7/24 14:24, Manos Pitsidianakis wrote:
> On Wed, 03 Jul 2024 11:59, Philippe Mathieu-Daudé <philmd@linaro.org> 
> wrote:
> > "General command" (GEN_CMD, CMD56) is described as:
> >
> >  GEN_CMD is the same as the single block read or write
> >  commands (CMD24 or CMD17). The difference is that [...]
> >  the data block is not a memory payload data but has a
> >  vendor specific format and meaning.
> >
> > Thus this block must not be stored overwriting data block
> > on underlying storage drive. Keep it in a dedicated
> > 'vendor_data[]' array.
>
>
> I am reading the 4.3 spec, and it says:
>
>   The bus transaction of the GEN_CMD is the same as the single block 
>   read or write commands (CMD24 or CMD17). The difference is that the 
>   argument denotes the direction of the data transfer (rather than the 
>   address) and the data block is not a memory payload data but has a 
>   vendor specific format and meaning.
>
> The vendor here (qemu) does not support any functionality with CMD56. I 
> think the correct approach would be to read zeros and discard writes, 
> without storing anything and without changing data_offset (which is for 
> `data` buffer)
>
> What do you think?

As Luc suggested in v42. Indeed simpler thus clever.

> > Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> > ---
> > v43: Do not re-use VMSTATE_UNUSED_V (danpb)
> > v44: Use subsection (Luc)
> > v45: Remove APP_READ_BLOCK/APP_WRITE_BLOCK macros
> > ---
> > hw/sd/sd.c | 29 +++++++++++++++++++----------
> > 1 file changed, 19 insertions(+), 10 deletions(-)