Re: [edk2-devel] [PATCH 3/4] OvmfPkg/VirtNorFlashDxe: allow larger writes without block erase

["Ard Biesheuvel" <ardb@kernel.org>]

On Fri, 12 Jan 2024 at 12:38, Gerd Hoffmann <kraxel@redhat.com> wrote:
>
> Raise the limit for writes without block erase from two to four
> P30_MAX_BUFFER_SIZE_IN_BYTES blocks.  With this in place almost
> all efi variable updates are handled without block erase.  With
> the old limit some variable updates (with device paths) took the
> block erase code path.
>
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>  OvmfPkg/VirtNorFlashDxe/VirtNorFlash.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/OvmfPkg/VirtNorFlashDxe/VirtNorFlash.c b/OvmfPkg/VirtNorFlashDxe/VirtNorFlash.c
> index 90db12716a4c..c631ffd3a62d 100644
> --- a/OvmfPkg/VirtNorFlashDxe/VirtNorFlash.c
> +++ b/OvmfPkg/VirtNorFlashDxe/VirtNorFlash.c
> @@ -555,7 +555,7 @@ NorFlashWriteSingleBlock (
>    // To avoid pathological cases were a 2 byte write is disregarded because it
>    // occurs right at a 128 byte buffered write alignment boundary, permit up to
>    // twice the max buffer size, and perform two writes if needed.

Please update the comment

> -  if ((*NumBytes + (Offset & BOUNDARY_OF_32_WORDS)) <= (2 * P30_MAX_BUFFER_SIZE_IN_BYTES)) {
> +  if ((*NumBytes + (Offset & BOUNDARY_OF_32_WORDS)) <= (4 * P30_MAX_BUFFER_SIZE_IN_BYTES)) {
>      // Check to see if we need to erase before programming the data into NOR.
>      // If the destination bits are only changing from 1s to 0s we can just write.
>      // After a block is erased all bits in the block is set to 1.


Reviewed-by: Ard Biesheuvel <ardb@kernel.org>


-=-=-=-=-=-=-=-=-=-=-=-
Groups.io Links: You receive all messages sent to this group.
View/Reply Online (#113728): https://edk2.groups.io/g/devel/message/113728
Mute This Topic: https://groups.io/mt/103680934/7686176
Group Owner: devel+owner@edk2.groups.io
Unsubscribe: https://edk2.groups.io/g/devel/unsub [rebecca@openfw.io]
-=-=-=-=-=-=-=-=-=-=-=-