Re: [Qemu-devel] [PATCH] block: mask NOR flash buffered write length

[Stefan Hajnoczi]

On Thu, Oct 17, 2013 at 07:30:02PM -0700, Roy Franz wrote:
> For buffered writes, mask the length with the maximum supported
> length.  This is required for block writes to work on the ARM vexpress
> platform, where the flash interface is 32 bits wide.  For buffered writes
> to the 2 16 bit flashes on the interface, the length is repeated in each
> 16 bit word, and without this mask the two lengths are interpreted 
> as a single 32 bit value that is very large.
> 
> Signed-off-by: Roy Franz <address@hidden>
> ---
>  hw/block/pflash_cfi01.c |    1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/hw/block/pflash_cfi01.c b/hw/block/pflash_cfi01.c
> index 018a967..a364cca 100644
> --- a/hw/block/pflash_cfi01.c
> +++ b/hw/block/pflash_cfi01.c
> @@ -378,6 +378,7 @@ static void pflash_write(pflash_t *pfl, hwaddr offset,
>  
>              break;
>          case 0xe8:
> +            value &= pfl->writeblock_size - 1;

This patch feels weird.   Should the 32-bit interface width be truncated
down to 16 bits before dispatching pflash_write()?

It's not clear to me that truncating just in this specific case is
correct.  But then I don't know the hardware :).

Stefan