| Message ID | 095b1f20091f8cf18565a3700372fa65736f0d0a.1338911144.git.phrdina@redhat.com |
|---|---|
| State | New |
| Headers | show |
Sorry, I forget the qtest. I'll create it and send it again. Pavel On 06/05/2012 05:46 PM, Pavel Hrdina wrote: > The Windows uses 'READ' command at the start of an instalation > without checking the 'dir' register. We have to abort the transfer > with an abnormal termination if there is no media in the drive. > > We have to also check the 'media_change' bit in the 'fd_seek'. This > internal seek clears the 'media_change' bit, too, if there is > a media inserted. > > Signed-off-by: Pavel Hrdina<phrdina@redhat.com> > --- > hw/fdc.c | 7 ++++++- > 1 files changed, 6 insertions(+), 1 deletions(-) > > diff --git a/hw/fdc.c b/hw/fdc.c > index 30d34e3..2d6dd30 100644 > --- a/hw/fdc.c > +++ b/hw/fdc.c > @@ -127,8 +127,13 @@ static int fd_seek(FDrive *drv, uint8_t head, uint8_t track, uint8_t sect, > uint32_t sector; > int ret; > > + if (drv->bs != NULL&& bdrv_is_inserted(drv->bs)) { > + drv->media_changed = 0; > + } > + > if (track> drv->max_track || > - (head != 0&& (drv->flags& FDISK_DBL_SIDES) == 0)) { > + (head != 0&& (drv->flags& FDISK_DBL_SIDES) == 0) || > + drv->media_changed) { > FLOPPY_DPRINTF("try to read %d %02x %02x (max=%d %d %02x %02x)\n", > head, track, sect, 1, > (drv->flags& FDISK_DBL_SIDES) == 0 ? 0 : 1,
Am 05.06.2012 17:50, schrieb Pavel Hrdina: > Sorry, I forget the qtest. I'll create it and send it again. > > Pavel > > On 06/05/2012 05:46 PM, Pavel Hrdina wrote: >> The Windows uses 'READ' command at the start of an instalation >> without checking the 'dir' register. We have to abort the transfer >> with an abnormal termination if there is no media in the drive. >> >> We have to also check the 'media_change' bit in the 'fd_seek'. This >> internal seek clears the 'media_change' bit, too, if there is >> a media inserted. >> >> Signed-off-by: Pavel Hrdina<phrdina@redhat.com> >> --- >> hw/fdc.c | 7 ++++++- >> 1 files changed, 6 insertions(+), 1 deletions(-) >> >> diff --git a/hw/fdc.c b/hw/fdc.c >> index 30d34e3..2d6dd30 100644 >> --- a/hw/fdc.c >> +++ b/hw/fdc.c >> @@ -127,8 +127,13 @@ static int fd_seek(FDrive *drv, uint8_t head, uint8_t track, uint8_t sect, >> uint32_t sector; >> int ret; >> >> + if (drv->bs != NULL&& bdrv_is_inserted(drv->bs)) { >> + drv->media_changed = 0; >> + } >> + >> if (track> drv->max_track || >> - (head != 0&& (drv->flags& FDISK_DBL_SIDES) == 0)) { >> + (head != 0&& (drv->flags& FDISK_DBL_SIDES) == 0) || >> + drv->media_changed) { Why not directly use bdrv_is_inserted() here? Fiddling around with media_changed feels rather hacky and is strictly speaking incorrect because a step pulse is not guaranteed to happen in the following code. The floppy code doesn't get it quite right today anyway, but a hack like this would contribute to the problem. >> FLOPPY_DPRINTF("try to read %d %02x %02x (max=%d %d %02x %02x)\n", >> head, track, sect, 1, >> (drv->flags& FDISK_DBL_SIDES) == 0 ? 0 : 1, Kevin
On 06/05/2012 05:56 PM, Kevin Wolf wrote: > Am 05.06.2012 17:50, schrieb Pavel Hrdina: >> Sorry, I forget the qtest. I'll create it and send it again. >> >> Pavel >> >> On 06/05/2012 05:46 PM, Pavel Hrdina wrote: >>> The Windows uses 'READ' command at the start of an instalation >>> without checking the 'dir' register. We have to abort the transfer >>> with an abnormal termination if there is no media in the drive. >>> >>> We have to also check the 'media_change' bit in the 'fd_seek'. This >>> internal seek clears the 'media_change' bit, too, if there is >>> a media inserted. >>> >>> Signed-off-by: Pavel Hrdina<phrdina@redhat.com> >>> --- >>> hw/fdc.c | 7 ++++++- >>> 1 files changed, 6 insertions(+), 1 deletions(-) >>> >>> diff --git a/hw/fdc.c b/hw/fdc.c >>> index 30d34e3..2d6dd30 100644 >>> --- a/hw/fdc.c >>> +++ b/hw/fdc.c >>> @@ -127,8 +127,13 @@ static int fd_seek(FDrive *drv, uint8_t head, uint8_t track, uint8_t sect, >>> uint32_t sector; >>> int ret; >>> >>> + if (drv->bs != NULL&& bdrv_is_inserted(drv->bs)) { >>> + drv->media_changed = 0; >>> + } >>> + >>> if (track> drv->max_track || >>> - (head != 0&& (drv->flags& FDISK_DBL_SIDES) == 0)) { >>> + (head != 0&& (drv->flags& FDISK_DBL_SIDES) == 0) || >>> + drv->media_changed) { > Why not directly use bdrv_is_inserted() here? > > Fiddling around with media_changed feels rather hacky and is strictly > speaking incorrect because a step pulse is not guaranteed to happen in > the following code. The floppy code doesn't get it quite right today > anyway, but a hack like this would contribute to the problem. > > >>> FLOPPY_DPRINTF("try to read %d %02x %02x (max=%d %d %02x %02x)\n", >>> head, track, sect, 1, >>> (drv->flags& FDISK_DBL_SIDES) == 0 ? 0 : 1, > Kevin > I'll move the code into the end of 'fd_seek' function, where a step is guaranteed. Internal seek should also reset the 'media_changed' bit if there is a media in the drive. I'll create the qtest tomorrow then I'll send another version of this patch. Pavel
Am 05.06.2012 18:34, schrieb Pavel Hrdina: > On 06/05/2012 05:56 PM, Kevin Wolf wrote: >> Am 05.06.2012 17:50, schrieb Pavel Hrdina: >>> Sorry, I forget the qtest. I'll create it and send it again. >>> >>> Pavel >>> >>> On 06/05/2012 05:46 PM, Pavel Hrdina wrote: >>>> The Windows uses 'READ' command at the start of an instalation >>>> without checking the 'dir' register. We have to abort the transfer >>>> with an abnormal termination if there is no media in the drive. >>>> >>>> We have to also check the 'media_change' bit in the 'fd_seek'. This >>>> internal seek clears the 'media_change' bit, too, if there is >>>> a media inserted. >>>> >>>> Signed-off-by: Pavel Hrdina<phrdina@redhat.com> >>>> --- >>>> hw/fdc.c | 7 ++++++- >>>> 1 files changed, 6 insertions(+), 1 deletions(-) >>>> >>>> diff --git a/hw/fdc.c b/hw/fdc.c >>>> index 30d34e3..2d6dd30 100644 >>>> --- a/hw/fdc.c >>>> +++ b/hw/fdc.c >>>> @@ -127,8 +127,13 @@ static int fd_seek(FDrive *drv, uint8_t head, uint8_t track, uint8_t sect, >>>> uint32_t sector; >>>> int ret; >>>> >>>> + if (drv->bs != NULL&& bdrv_is_inserted(drv->bs)) { >>>> + drv->media_changed = 0; >>>> + } >>>> + >>>> if (track> drv->max_track || >>>> - (head != 0&& (drv->flags& FDISK_DBL_SIDES) == 0)) { >>>> + (head != 0&& (drv->flags& FDISK_DBL_SIDES) == 0) || >>>> + drv->media_changed) { >> Why not directly use bdrv_is_inserted() here? >> >> Fiddling around with media_changed feels rather hacky and is strictly >> speaking incorrect because a step pulse is not guaranteed to happen in >> the following code. The floppy code doesn't get it quite right today >> anyway, but a hack like this would contribute to the problem. >> >> >>>> FLOPPY_DPRINTF("try to read %d %02x %02x (max=%d %d %02x %02x)\n", >>>> head, track, sect, 1, >>>> (drv->flags& FDISK_DBL_SIDES) == 0 ? 0 : 1, >> Kevin >> > I'll move the code into the end of 'fd_seek' function, where a step is > guaranteed. Internal seek should also reset the 'media_changed' bit if > there is a media in the drive. I'll create the qtest tomorrow then I'll > send another version of this patch. My point is that the success of a seek has nothing to do with the DSKCHG signal. Even if you move the code around, DSKCHG may start to coincide with the condition you really want to check, but it's logically still not what should be checked. What's wrong with !bdrv_is_inserted() in the if condition? If something is wrong with the media_changed handling, then it's a separate bug that should be dealt with in a separate patch. Kevin
On 06/06/2012 12:35 PM, Kevin Wolf wrote: > Am 05.06.2012 18:34, schrieb Pavel Hrdina: >> On 06/05/2012 05:56 PM, Kevin Wolf wrote: >>> Am 05.06.2012 17:50, schrieb Pavel Hrdina: >>>> Sorry, I forget the qtest. I'll create it and send it again. >>>> >>>> Pavel >>>> >>>> On 06/05/2012 05:46 PM, Pavel Hrdina wrote: >>>>> The Windows uses 'READ' command at the start of an instalation >>>>> without checking the 'dir' register. We have to abort the transfer >>>>> with an abnormal termination if there is no media in the drive. >>>>> >>>>> We have to also check the 'media_change' bit in the 'fd_seek'. This >>>>> internal seek clears the 'media_change' bit, too, if there is >>>>> a media inserted. >>>>> >>>>> Signed-off-by: Pavel Hrdina<phrdina@redhat.com> >>>>> --- >>>>> hw/fdc.c | 7 ++++++- >>>>> 1 files changed, 6 insertions(+), 1 deletions(-) >>>>> >>>>> diff --git a/hw/fdc.c b/hw/fdc.c >>>>> index 30d34e3..2d6dd30 100644 >>>>> --- a/hw/fdc.c >>>>> +++ b/hw/fdc.c >>>>> @@ -127,8 +127,13 @@ static int fd_seek(FDrive *drv, uint8_t head, uint8_t track, uint8_t sect, >>>>> uint32_t sector; >>>>> int ret; >>>>> >>>>> + if (drv->bs != NULL&& bdrv_is_inserted(drv->bs)) { >>>>> + drv->media_changed = 0; >>>>> + } >>>>> + >>>>> if (track> drv->max_track || >>>>> - (head != 0&& (drv->flags& FDISK_DBL_SIDES) == 0)) { >>>>> + (head != 0&& (drv->flags& FDISK_DBL_SIDES) == 0) || >>>>> + drv->media_changed) { >>> Why not directly use bdrv_is_inserted() here? >>> >>> Fiddling around with media_changed feels rather hacky and is strictly >>> speaking incorrect because a step pulse is not guaranteed to happen in >>> the following code. The floppy code doesn't get it quite right today >>> anyway, but a hack like this would contribute to the problem. >>> >>> >>>>> FLOPPY_DPRINTF("try to read %d %02x %02x (max=%d %d %02x %02x)\n", >>>>> head, track, sect, 1, >>>>> (drv->flags& FDISK_DBL_SIDES) == 0 ? 0 : 1, >>> Kevin >>> >> I'll move the code into the end of 'fd_seek' function, where a step is >> guaranteed. Internal seek should also reset the 'media_changed' bit if >> there is a media in the drive. I'll create the qtest tomorrow then I'll >> send another version of this patch. > My point is that the success of a seek has nothing to do with the DSKCHG > signal. Even if you move the code around, DSKCHG may start to coincide > with the condition you really want to check, but it's logically still > not what should be checked. What's wrong with !bdrv_is_inserted() in the > if condition? > > If something is wrong with the media_changed handling, then it's a > separate bug that should be dealt with in a separate patch. > > Kevin I don't think that is true. Please read this http://wiki.osdev.org/Floppy_Disk_Controller#DIR_register.2C_Disk_Change_bit and http://wiki.osdev.org/Floppy_Disk_Controller#Seek . Directly it has nothing to do with DSKCHG bit, but indirectly seek to different cylinder fails if there is no media in drive on real FDC. Only successful seek to different cylinder clears the DSKCHG bit. That's why I do it this way, because in our FDC emulation we clears the DSKCHG bit or not also if you seek to the same cylinder. The function 'fd_seek' stands for implied seek which also clears the DSKCHG bit. Pavel
Am 06.06.2012 15:43, schrieb Pavel Hrdina: >>> I'll move the code into the end of 'fd_seek' function, where a step is >>> guaranteed. Internal seek should also reset the 'media_changed' bit if >>> there is a media in the drive. I'll create the qtest tomorrow then I'll >>> send another version of this patch. >> My point is that the success of a seek has nothing to do with the DSKCHG >> signal. Even if you move the code around, DSKCHG may start to coincide >> with the condition you really want to check, but it's logically still >> not what should be checked. What's wrong with !bdrv_is_inserted() in the >> if condition? >> >> If something is wrong with the media_changed handling, then it's a >> separate bug that should be dealt with in a separate patch. >> >> Kevin > I don't think that is true. Please read this > http://wiki.osdev.org/Floppy_Disk_Controller#DIR_register.2C_Disk_Change_bit > and http://wiki.osdev.org/Floppy_Disk_Controller#Seek . Directly it has > nothing to do with DSKCHG bit, but indirectly seek to different cylinder > fails if there is no media in drive on real FDC. Only successful seek to > different cylinder clears the DSKCHG bit. If you have the choice between a direct way (bdrv_is_inserted) and an indirect one (DSKCHG), you should always use the directly related one. It makes the intention of the code clearer and is less likely to break, because you actually said what you want and not just something that you believe happens at the same time. So your explanation confirms for me that the check should be whether a medium is in the drive, i.e. bdrv_is_inserted(). > That's why I do it this way, because in our FDC emulation we clears the > DSKCHG bit or not also if you seek to the same cylinder. The function > 'fd_seek' stands for implied seek which also clears the DSKCHG bit. That the DSKCHG bit is cleared even if the head doesn't move is a bug in our code. I accepted Hervé's patches because they were a big improvement, but they don't implement quite correct behaviour yet. Relying on buggy behaviour is obviously wrong. Anyway, I'm not arguing against clearing DSKCHG in this function. I just say that it addresses an unrelated problem and should be posted in a different patch. And even then the updated DSKCHG isn't directly related to the check you're introducing in this patch, so it still would have to stay bdrv_is_inserted() there. Kevin
diff --git a/hw/fdc.c b/hw/fdc.c index 30d34e3..2d6dd30 100644 --- a/hw/fdc.c +++ b/hw/fdc.c @@ -127,8 +127,13 @@ static int fd_seek(FDrive *drv, uint8_t head, uint8_t track, uint8_t sect, uint32_t sector; int ret; + if (drv->bs != NULL && bdrv_is_inserted(drv->bs)) { + drv->media_changed = 0; + } + if (track > drv->max_track || - (head != 0 && (drv->flags & FDISK_DBL_SIDES) == 0)) { + (head != 0 && (drv->flags & FDISK_DBL_SIDES) == 0) || + drv->media_changed) { FLOPPY_DPRINTF("try to read %d %02x %02x (max=%d %d %02x %02x)\n", head, track, sect, 1, (drv->flags & FDISK_DBL_SIDES) == 0 ? 0 : 1,
The Windows uses 'READ' command at the start of an instalation without checking the 'dir' register. We have to abort the transfer with an abnormal termination if there is no media in the drive. We have to also check the 'media_change' bit in the 'fd_seek'. This internal seek clears the 'media_change' bit, too, if there is a media inserted. Signed-off-by: Pavel Hrdina <phrdina@redhat.com> --- hw/fdc.c | 7 ++++++- 1 files changed, 6 insertions(+), 1 deletions(-)