Re: [Qemu-block] [PATCH] pflash: Only read non-zero parts of backend image

[Peter Maydell]

On Sun, 5 May 2019 at 08:02, Xiang Zheng <address@hidden> wrote:
>
> Currently we fill the memory space with two 64MB NOR images when
> using persistent UEFI variables on virt board. Actually we only use
> a very small(non-zero) part of the memory while the rest significant
> large(zero) part of memory is wasted.
>
> So this patch checks the block status and only writes the non-zero part
> into memory. This requires pflash devices to use sparse files for
> backends.

Do you mean "pflash devices will no longer work if the file
that is backing them is not sparse", or just "if the file that
is backing them is not sparse then you won't get the benefit
of using less memory" ?

thanks
-- PMM