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

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

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(-)