This is a discussion on Re: wscons for FreeBSD? - FreeBSD ; Kris Kennaway wrote: > > On Fri, Oct 28, 2005 at 09:50:49PM -0600, M. Warner Losh wrote: > > In message: > > Sergey Babkin writes: > > : John Baldwin wrote: > > : > > > : > ...
Kris Kennaway wrote:
> On Fri, Oct 28, 2005 at 09:50:49PM -0600, M. Warner Losh wrote:
> > In message: <4362B611.B4A12AF8@verizon.net>
> > Sergey Babkin
> > : John Baldwin wrote:
> > : >
> > : > On Friday 28 October 2005 01:24 pm, Sergey Babkin wrote:
> > : > > >From: John Baldwin
> > : > > >
> > :
> > : > > * When entering panic/debugger mode the console
> > : > > should reset its video mode to the one where
> > : > > the panic information is visible.
> > : >
> > : > I think this might be kind of hard since you really don't know what X has done
> > : > to the hardware unless you make X talk to the console driver to do
> > : > everything.
> > :
> > : Can you re-initialize the device from scratch? My knowledge
> > : about the video hardware dates to SVGA times and even that
> > : is not too deep.
> > :
> > : Maybe provide a basic SVGA re-initialization routine on x86 and have
> > : an interface for the third-party in-kernel drivers that
> > : would contain the re-initialization routine.
> > When this has come up in the past, those in the know say that it takes
> > card specific registers and knowledge to reset these cards' video
> > modes.
> Even if it doesn't work on all cards, if there's some method that will
> at least work for a subset of configurations it may be worth
> investigating: by that point the machine has panicked anyway, so
> what's the worst that can happen?
I think that if there are no endless busy waits, nothing should make
the situation any worse.
I guess for VESA-compatible cards the VESA BIOS couls be used too,
but that's much more complicated to do and much more prone to
things going wrong during resets.
But I guess in any case providing an interface for the in-kernel reset
drivers would solve the problem as long as there are those drivers.
Their implementation can probably be extracted from XF86, though
of course it would need extra work.
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