Re: [PATCH 2/4] hw/block/fdc: Remove the check_media_rate property

[John Snow]

On 2/13/21 5:41 PM, Laurent Vivier wrote:
> Le 08/02/2021 à 08:05, Thomas Huth a écrit :
> > On 05/02/2021 21.15, John Snow wrote:
> > > On 2/5/21 1:37 AM, Thomas Huth wrote:
> > > > On 05/02/2021 01.40, John Snow wrote:
> > > > > On 2/3/21 12:18 PM, Thomas Huth wrote:
> > > > > > This was only required for the pc-1.0 and earlier machine types.
> > > > > > Now that these have been removed, we can also drop the corresponding
> > > > > > code from the FDC device.
> > > > > >
> > > > > > Signed-off-by: Thomas Huth <thuth@redhat.com>
> > > > > > ---
> > > > > >    hw/block/fdc.c             | 17 ++---------------
> > > > > >    tests/qemu-iotests/172.out | 35 -----------------------------------
> > > > > >    2 files changed, 2 insertions(+), 50 deletions(-)
> > > > > >
> > > > > > diff --git a/hw/block/fdc.c b/hw/block/fdc.c
> > > > > > index 292ea87805..198940e737 100644
> > > > > > --- a/hw/block/fdc.c
> > > > > > +++ b/hw/block/fdc.c
> > > > > > @@ -874,7 +874,6 @@ struct FDCtrl {
> > > > > >            FloppyDriveType type;
> > > > > >        } qdev_for_drives[MAX_FD];
> > > > > >        int reset_sensei;
> > > > > > -    uint32_t check_media_rate;
> > > > >
> > > > > I am a bit of a dunce when it comes to the compatibility properties... does 
> > > > > this mess with the
> > > > > migration format?
> > > > >
> > > > > I guess it doesn't, since it's not in the VMSTATE declaration.
> > > > >
> > > > > Hmmmm, alright.
> > > >
> > > > I think that should be fine, yes.
> > > >
> > > > > >        FloppyDriveType fallback; /* type=auto failure fallback */
> > > > > >        /* Timers state */
> > > > > >        uint8_t timer0;
> > > > > > @@ -1021,18 +1020,10 @@ static const VMStateDescription 
> > > > > > vmstate_fdrive_media_changed = {
> > > > > >        }
> > > > > >    };
> > > > > > -static bool fdrive_media_rate_needed(void *opaque)
> > > > > > -{
> > > > > > -    FDrive *drive = opaque;
> > > > > > -
> > > > > > -    return drive->fdctrl->check_media_rate;
> > > > > > -}
> > > > > > -
> > > > > >    static const VMStateDescription vmstate_fdrive_media_rate = {
> > > > > >        .name = "fdrive/media_rate",
> > > > > >        .version_id = 1,
> > > > > >        .minimum_version_id = 1,
> > > > > > -    .needed = fdrive_media_rate_needed,
> > > > > >        .fields = (VMStateField[]) {
> > > > > >            VMSTATE_UINT8(media_rate, FDrive),
> > > > > >            VMSTATE_END_OF_LIST()
> > > > > > @@ -1689,8 +1680,7 @@ static void fdctrl_start_transfer(FDCtrl *fdctrl, int 
> > > > > > direction)
> > > > > >        /* Check the data rate. If the programmed data rate does not match
> > > > > >         * the currently inserted medium, the operation has to fail. */
> > > > > > -    if (fdctrl->check_media_rate &&
> > > > > > -        (fdctrl->dsr & FD_DSR_DRATEMASK) != cur_drv->media_rate) {
> > > > > > +    if ((fdctrl->dsr & FD_DSR_DRATEMASK) != cur_drv->media_rate) {
> > > > > >            FLOPPY_DPRINTF("data rate mismatch (fdc=%d, media=%d)\n",
> > > > > >                           fdctrl->dsr & FD_DSR_DRATEMASK, cur_drv->media_rate);
> > > > > >            fdctrl_stop_transfer(fdctrl, FD_SR0_ABNTERM, FD_SR1_MA, 0x00);
> > > > > > @@ -2489,8 +2479,7 @@ static void fdctrl_result_timer(void *opaque)
> > > > > >            cur_drv->sect = (cur_drv->sect % cur_drv->last_sect) + 1;
> > > > > >        }
> > > > > >        /* READ_ID can't automatically succeed! */
> > > > > > -    if (fdctrl->check_media_rate &&
> > > > > > -        (fdctrl->dsr & FD_DSR_DRATEMASK) != cur_drv->media_rate) {
> > > > > > +    if ((fdctrl->dsr & FD_DSR_DRATEMASK) != cur_drv->media_rate) {
> > > > > >            FLOPPY_DPRINTF("read id rate mismatch (fdc=%d, media=%d)\n",
> > > > > >                           fdctrl->dsr & FD_DSR_DRATEMASK, cur_drv->media_rate);
> > > > > >            fdctrl_stop_transfer(fdctrl, FD_SR0_ABNTERM, FD_SR1_MA, 0x00);
> > > > > > @@ -2895,8 +2884,6 @@ static Property isa_fdc_properties[] = {
> > > > > >        DEFINE_PROP_UINT32("dma", FDCtrlISABus, dma, 2),
> > > > > >        DEFINE_PROP_DRIVE("driveA", FDCtrlISABus, state.qdev_for_drives[0].blk),
> > > > > >        DEFINE_PROP_DRIVE("driveB", FDCtrlISABus, state.qdev_for_drives[1].blk),
> > > > > > -    DEFINE_PROP_BIT("check_media_rate", FDCtrlISABus, state.check_media_rate,
> > > > > > -                    0, true),
> > > > >
> > > > > Could you theoretically set this via QOM commands in QMP, and claim that this 
> > > > > is a break in
> > > > > behavior?
> > > > >
> > > > > Though, it's ENTIRELY undocumented, so ... it's probably fine, I think. 
> > > > > Probably. (Please soothe
> > > > > my troubled mind.)
> > > >
> > > > A user actually could mess with this property even on the command line, e.g. by 
> > > > using:
> > > >
> > > >    qemu-system-x86_64 -global isa-fdc.check_media_rate=false
> > > >
> > > > ... but, as you said, it's completely undocumented, the property is really just 
> > > > there for the
> > > > internal use of machine type compatibility. We've done such clean-ups in the 
> > > > past already, see
> > > > e.g. c6026998eef382d7ad76 or 2a4dbaf1c0db2453ab78f, so I think this should be 
> > > > fine. But if you
> > > > disagree, I could replace this by a patch that adds this property to the list 
> > > > of deprecated
> > > > features instead, so we could at least remove it after it has been deprecated 
> > > > for two releases?
> > >
> > > I don't think it's necessary, personally -- just wanted to make sure I knew the 
> > > exact stakes here.
> > >
> > > Reviewed-by: John Snow <jsnow@redhat.com>
> > > Acked-by: John Snow <jsnow@redhat.com>
> >
> > Thanks! ... since the first patch has already been merged through Michael's 
> > tree, could you then
> > please take this patch here through your floppy / block branch, John? Or maybe 
> > it could also go via
> > qemu-trivial?
>
> Applied to my trivial-patches branch.
>
> Thanks,
> Laurent

Thank you, Laurent!

--js