Re: [Qemu-devel] [RFC 6/7] Add offset register to fw_cfg DMA interface

[Laszlo Ersek <lersek@redhat.com>]

On 07/21/15 18:26, Stefan Hajnoczi wrote:
> On Tue, Jul 21, 2015 at 5:03 PM, Marc Marí <markmb@redhat.com> wrote:
>> Signed-off-by: Marc Marí <markmb@redhat.com>
>> ---
>>  hw/nvram/fw_cfg.c | 19 ++++++++++++++++---
>>  1 file changed, 16 insertions(+), 3 deletions(-)
> 
> No commit description, no docs/specs/fw_cfg.txt documentation.

Yes, those would be nice.

Also, I think this patch should be squashed into the main fw_cfg patch.

> I understand how the offset is supposed to work, but why is it
> necessary?  No one needed it before so there must be a reason why you
> decided to add it now.

I guess because of
<http://thread.gmane.org/gmane.comp.bios.coreboot.seabios/9496/focus=9554>.

For me chunked transfers would be important (ie. transfering I+J=K bytes
from the same fw_cfg file should be possible as two separate accesses,
with I & J sizes), but I believe the offset register would not be
necessary just for that. So I think it's solely directed at Kevin's
feedback (see link above).

Thanks
Laszlo