RE: [PATCH v2 01/22] block: add eMMC block device type

[Sai Pavan Boddu <saipava@xilinx.com>]

Hi Philippe,

> -----Original Message-----
> From: Philippe Mathieu-Daudé <philmd@redhat.com>
> Sent: Monday, February 22, 2021 6:54 PM
> To: Dr. David Alan Gilbert <dgilbert@redhat.com>; Markus Armbruster
> <armbru@redhat.com>
> Cc: Sai Pavan Boddu <saipava@xilinx.com>; Kevin Wolf <kwolf@redhat.com>;
> Max Reitz <mreitz@redhat.com>; Vladimir Sementsov-Ogievskiy
> <vsementsov@virtuozzo.com>; Eric Blake <eblake@redhat.com>; Joel Stanley
> <joel@jms.id.au>; Cédric Le Goater <clg@kaod.org>; Vincent Palatin
> <vpalatin@chromium.org>; Thomas Huth <thuth@redhat.com>; Stefan
> Hajnoczi <stefanha@redhat.com>; Peter Maydell <peter.maydell@linaro.org>;
> Alistair Francis <alistair.francis@wdc.com>; Edgar Iglesias <edgari@xilinx.com>;
> Luc Michel <luc.michel@greensocs.com>; Paolo Bonzini
> <pbonzini@redhat.com>; Sai Pavan Boddu <saipava@xilinx.com>; qemu-
> devel@nongnu.org; qemu-block@nongnu.org
> Subject: Re: [PATCH v2 01/22] block: add eMMC block device type
> 
> On 2/22/21 2:16 PM, Dr. David Alan Gilbert wrote:
> > * Markus Armbruster (armbru@redhat.com) wrote:
> >> Philippe Mathieu-Daudé <philmd@redhat.com> writes:
> >>
> >>> On 2/22/21 9:20 AM, Sai Pavan Boddu wrote:
> >>>> From: Vincent Palatin <vpalatin@chromium.org>
> >>>>
> >>>> Add new block device type.
> >>>>
> >>>> Signed-off-by: Vincent Palatin <vpalatin@chromium.org>
> >>>> [SPB: Rebased over 5.1 version]
> >>>> Signed-off-by: Sai Pavan Boddu <sai.pavan.boddu@xilinx.com>
> >>>> Signed-off-by: Joel Stanley <joel@jms.id.au>
> >>>> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> >>>> Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
> >>>> ---
> >>>>  include/sysemu/blockdev.h | 1 +
> >>>>  blockdev.c                | 1 +
> >>>>  2 files changed, 2 insertions(+)
> >>>>
> >>>> diff --git a/include/sysemu/blockdev.h b/include/sysemu/blockdev.h
> >>>> index 3b5fcda..eefae9f 100644
> >>>> --- a/include/sysemu/blockdev.h
> >>>> +++ b/include/sysemu/blockdev.h
> >>>> @@ -24,6 +24,7 @@ typedef enum {
> >>>>       */
> >>>>      IF_NONE = 0,
> >>>>      IF_IDE, IF_SCSI, IF_FLOPPY, IF_PFLASH, IF_MTD, IF_SD,
> >>>> IF_VIRTIO, IF_XEN,
> >>>> +    IF_EMMC,
> >>>>      IF_COUNT
> >>>>  } BlockInterfaceType;
> >>>>
> >>>> diff --git a/blockdev.c b/blockdev.c index cd438e6..390d43c 100644
> >>>> --- a/blockdev.c
> >>>> +++ b/blockdev.c
> >>>> @@ -83,6 +83,7 @@ static const char *const if_name[IF_COUNT] = {
> >>>>      [IF_SD] = "sd",
> >>>>      [IF_VIRTIO] = "virtio",
> >>>>      [IF_XEN] = "xen",
> >>>> +    [IF_EMMC] = "emmc",
> >>>>  };
> >>>
> >>> We don't need to introduce support for the legacy -drive magic.
> >>>
> >>> -device should be enough for this device, right?
> >>
> >> External interface extensions need rationale: why do we want / need it?
> >> The commit message neglects to provide one.
> >>
> >> Even more so when the interface in question is in a state like -drive
> >> is.
> >
> > I wouldn't be too nasty about -drive;  for me I still find it the
> > easiest way to start a VM.
> 
> But eMMC isn't a bus where you can plug drives, it is soldered on-board and is
> mmio mapped to a fixed address. I don't see the point of having a drive
> interface for it...
[Sai Pavan Boddu] Yeah, this makes sense but having a drive would be a simple implementation without disturbing much in the sd card emulation code. And its just easy to use, just as how sd cards are inserted.

I need to see, how easy it would be with -device.

Thanks,
Sai Pavan