linux-kernel - Re: [BUG] x86 kenel won't boot under Virtual PC

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Message-Id: <200809071922.32974.linux@sandersweb.net>
Date:	Sun, 7 Sep 2008 19:22:32 -0400
From:	David Sanders <linux@...dersweb.net>
To:	linux-kernel@...r.kernel.org, "H. Peter Anvin" <hpa@...or.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	the arch/x86 maintainers <x86@...nel.org>,
	Andi Kleen <andi-suse@...stfloor.org>
Subject: Re: [BUG] x86 kenel won't boot under Virtual PC

On Friday 05 September 2008 19:31, H. Peter Anvin wrote:
> David Sanders wrote:
> > I recently discovered that x86 kernels won't boot under Virtual PC.  In
>
> Could you please confirm if the tip kernel solves the problem?
>

Yes the patch you supplied (and now in Linus's tree) fixes (part) of the problem.
In order to get a working kernel I also need a patch for the nops.h issue.  
I have tested and confirmed that the patch posted by Linus works and finally 
solves the problem with virtual PC.

Linus please apply your patch (which I quote below).
---
 arch/x86/Kconfig.cpu |   13 ++++++++-----
 1 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu
index 2c518fb..b225219 100644
--- a/arch/x86/Kconfig.cpu
+++ b/arch/x86/Kconfig.cpu
@@ -382,14 +382,17 @@ config X86_OOSTORE
 # P6_NOPs are a relatively minor optimization that require a family >=
 # 6 processor, except that it is broken on certain VIA chips.
 # Furthermore, AMD chips prefer a totally different sequence of NOPs
-# (which work on all CPUs).  As a result, disallow these if we're
-# compiling X86_GENERIC but not X86_64 (these NOPs do work on all
-# x86-64 capable chips); the list of processors in the right-hand clause
-# are the cores that benefit from this optimization.
+# (which work on all CPUs).  In addition, it looks like Virtual PC
+# does not understand them.
+#
+# As a result, disallow these if we're not compiling for X86_64 (these
+# NOPs do work on all x86-64 capable chips); the list of processors in
+# the right-hand clause are the cores that benefit from this optimization.
 #
 config X86_P6_NOP
 	def_bool y
-	depends on (X86_64 || !X86_GENERIC) && (M686 || MPENTIUMII || MPENTIUMIII || MPENTIUMM || MCORE2 || MPENTIUM4 || MPSC)
+	depends on X86_64
+	depends on (MCORE2 || MPENTIUM4 || MPSC)
 
 config X86_TSC
 	def_bool y



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