Re: [PATCH 3/6] lguest suppress IDE probing

Matt Mackall
2007-06-07T14:45:40Z

On Thu, Jun 07, 2007 at 12:13:07PM +1000, Rusty Russell wrote:
> On Wed, 2007-06-06 at 11:23 +0100, Alan Cox wrote:
> > > > Better yet just don't compile in the old IDE stuff, lguest doesn't have a
> > > > PCI or ISA bus anyway.
> > >
> > > Sure, but the "run the same kernel as guest and host" is a really nice
> > > feature.
> >
> > Modules dear boy, modules ;)
>
> For some reason, pulling half the kernel's brains out into a separately
> maintained userspace seems to make things less reliable. I always build
> in everything I need to boot.
>
> Perhaps this makes me an old-timer.
>
> > > > Alternatively make the IDE I/O space return 0xFF and it'll skip them
> > > > anyway.
> > >
> > > Hmm, every "in" should be returning 0xFFs, but I still get the delay and
> > > the probing. Xen domU gets it too.
> >
> > Can you see in a debugger where it is spending the time. 0xFF should be
> > taken as "no port, move on nothing to see"
>
> Well, the code is a little opaque to me, but do_probe() calls msleep(50)
> three times. According to gdb this gets called 27 times -> 4.05
> seconds.

Yep. libata somehow manages to avoid most of these, it'd be
interesting to work out why.

--
Mathematics is the supreme nostalgia of our time.