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Subject: Re: [PATCH 3/6] lguest suppress IDE probing
From: Rusty Russell <rusty@rustcorp.com.au>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>,
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Date: Thu, 07 Jun 2007 12:13:07 +1000
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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.