Date: Thu, 24 Jul 2008 13:31:22 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86: fix pte_flags() to only return flags, fix lguest
	(updated)
Message-ID: <20080724113122.GB23262@elte.hu>
References: <200807221431.58991.rusty@rustcorp.com.au> <200807221540.47161.rusty@rustcorp.com.au> <20080722090432.GD2065@elte.hu> <200807231059.20810.rusty@rustcorp.com.au>
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* Rusty Russell <rusty@rustcorp.com.au> wrote:

> On Tuesday 22 July 2008 19:04:32 Ingo Molnar wrote:
> > i'm wondering. My randconfig tests boot up an lguest enabled kernel
> > every 30 minutes or so:
> >
> >  config-Mon_Jul_21_19_05_54_CEST_2008.good:CONFIG_LGUEST=y
> >  config-Mon_Jul_21_19_43_13_CEST_2008.good:CONFIG_LGUEST=y
> >  config-Mon_Jul_21_19_47_40_CEST_2008.good:CONFIG_LGUEST=y
> >  config-Mon_Jul_21_20_37_41_CEST_2008.good:CONFIG_LGUEST=y
> >  config-Mon_Jul_21_22_11_42_CEST_2008.good:CONFIG_LGUEST=y
> >  config-Mon_Jul_21_22_16_59_CEST_2008.good:CONFIG_LGUEST=y
> >  config-Mon_Jul_21_22_32_22_CEST_2008.good:CONFIG_LGUEST=y
> >  config-Mon_Jul_21_23_25_55_CEST_2008.good:CONFIG_LGUEST=y
> >  config-Mon_Jul_21_23_51_29_CEST_2008.good:CONFIG_LGUEST=y
> >
> > Would it be possible to have some really stupid lguest self-test which
> > would complain spectacularly in the host kernel if it fails to reach
> > some minimal user-space?
> >
> > Something that could be self-contained within a single bzImage. (i.e. it
> > would contain a minimalistic image of some sort with a very minimalistic
> > userspace component as well - or something like that)
> 
> Well, adding "make -C Documentation/lguest" to the build is a good start (this 
> finds those "e820.h not longer includable from userspace" bugs).
> 
> Secondly, if you put the resulting Documentation/lguest/lguest somewhere on 
> your booting test machine, it can just do something like
> 
> 	./lguest 64 /boot/vmlinuz-`uname -r` | grep 'VFS: Unable to mount root'

stupid question: what's the easiest way to filter out the case where 
there's not sufficient kernel support in the bzImage to actually run 
lguest?

I.e. if i extend the "is this bzImage working fine" check with the above 
lguest bootup test - with the expectation of it getting down to the 
"VFS: Unable to mount root" message [success case], how do i filter out 
the case where it doesnt get to that message not due to some lguest 
breakage, but because there's not enough lguest support there.

> Won't quite test userspace, but it's easy and will get the worst breakage.
> If we want to be more ambitious, I'd suggest a tiny initrd with a 
> statically-linked /hello_world to test userspace:
> 
> 	./lguest --initrd=/boot/hello_world.initrd 64 /boot/vmlinuz-`uname -r` \
> 		rdinit=/hello_world | grep 'Hello world'
> 
> I can create one (and test the example) for you if you're interested?

that would be great ...

	Ingo
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