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

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Date:	Thu, 07 Jun 2007 12:13:07 +1000
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	lkml - Kernel Mailing List <linux-kernel@...r.kernel.org>,
	bzolnier@...il.com, Matt Mackall <mpm@...enic.com>,
	Jeremy Fitzhardinge <jeremy@...p.org>
Subject: Re: [PATCH 3/6] lguest suppress IDE probing

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.

Cheers,
Rusty.


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