Re: [Qemu-block] [Qemu-devel] [PATCH] fdc: remove sparc sun4m mutations

[John Snow]

On 03/19/2015 10:25 AM, Mark Cave-Ayland wrote:
> On 17/03/15 06:43, Hervé Poussineau wrote:
>
> > Hi,
> >
> > Le 16/03/2015 22:48, John Snow a écrit :
> > > On 03/14/2015 12:50 PM, Hervé Poussineau wrote:
> > > > They were introduced in 6f7e9aec5eb5bdfa57a9e458e391b785c283a007 and
> > > > 82407d1a4035e5bfefb53ffdcb270872f813b34c and lots of bug fixes were
> > > > done after that.
> > > >
> > > > This fixes (at least) the detection of the floppy controller on
> > > > Debian 4.0r9/SPARC,
> > > > and SS-5's OBP initialization routine still works.
> > >
> > > Removing workaround code from six years ago in a device we hardly
> > > touch seems sane to me if it doesn't appear to break the machine it
> > > was originally architected for (SS-5, from 82407d1a's commit
> > > message), but I am not well versed in SPARC configurations,
> > > unfortunately for us :)
> > >
> > > It appears this quirk is active for a wide number of machine
> > > configurations (basically all that appear under sun4m_machine_init) --
> > > What's the risk of us breaking one of those configurations?
> > >
> > > How did you test SS-5? (Can we test the others similarly? Is there a
> > > justification for not doing so?)
> >
> > According to 82407d1a4035e5bfefb53ffdcb270872f813b34c, there was
> > probably a hang when SS-5 OBP firmware was initializing the floppy. I
> > checked my change with the OBP SS-5 firmware 2.15, which doesn't hang
> > and goes up to firmware prompt. I also tested SS-4, SS-10 (OBP v3.45)
> > and SS-20 (OBP 2.25) which also go up to firmware prompt. I was unable
> > to test the other platforms with OBP.
> > Then, I tested SS-5 with Debian 4.0r9, and boot messages now detect the
> > floppy controller with "Floppy drive(s): fd0 is 1.44M" and "FDC 0 is a
> > S82078B"
> >
> > However, in 82407d1a4035e5bfefb53ffdcb270872f813b34c, floppy was
> > probably not working, and is still broken after this commit. This may be
> > due to a missing DMA controller on sparc platform.
>
> Yeah, I'm fairly sure from Hervé's work in this area that the existing
> sun4m floppy disk could never function correctly anyway. Given that this
> is the case, I'd be okay with having this patch applied for all sun4m
> models so that it can at least be detected, and hopefully persuaded to
> work with only a little more effort.
>
>
> ATB,
>
> Mark.

Sounds good to me. Will stage for 2.4.

Thanks,
--js