From: Marcelo Tosatti <mtosatti@redhat•com>
To: Ingo Molnar <mingo@kernel•org>
Cc: "H. Peter Anvin" <hpa@zytor•com>,
"Michael S. Tsirkin" <mst@redhat•com>,
Avi Kivity <avi@redhat•com>, Randy Dunlap <rdunlap@xenotime•net>,
Stephen Rothwell <sfr@canb•auug.org.au>,
x86@kernel•org, kvm@vger•kernel.org, linux-next@vger•kernel.org,
linux-kernel@vger•kernel.org,
Thomas Gleixner <tglx@linutronix•de>,
Ingo Molnar <mingo@redhat•com>
Subject: Re: [PATCH] apic: fix kvm build on UP without IOAPIC
Date: Fri, 6 Jul 2012 08:32:09 -0300 [thread overview]
Message-ID: <20120706113209.GB18059@amt.cnet> (raw)
In-Reply-To: <20120706111314.GG19552@gmail.com>
On Fri, Jul 06, 2012 at 01:13:14PM +0200, Ingo Molnar wrote:
>
> * H. Peter Anvin <hpa@zytor•com> wrote:
>
> > On 07/01/2012 08:05 AM, Michael S. Tsirkin wrote:
> > >On UP i386, when APIC is disabled
> > ># CONFIG_X86_UP_APIC is not set
> > ># CONFIG_PCI_IOAPIC is not set
> > >
> > >code looking at apicdrivers never has any effect but it
> > >still gets compiled in. In particular, this causes
> > >build failures with kvm, but it generally bloats the kernel
> > >unnecessarily.
> > >
> > >Fix by defining both __apicdrivers and __apicdrivers_end
> > >to be NULL when CONFIG_X86_LOCAL_APIC is unset: I verified
> > >that as the result any loop scanning __apicdrivers gets optimized out by
> > >the compiler.
> > >
> > >Warning: a .config with apic disabled doesn't seem to boot
> > >for me (even without this patch). Still verifying why,
> > >meanwhile this patch is compile-tested only.
> > >
> > >Signed-off-by: Michael S. Tsirkin <mst@redhat•com>
> > >---
> > >
> > >Note: if this patch makes sense, can x86 maintainers
> > >please ACK applying it through the kvm tree, since that is
> > >where we see the issue that it addresses?
> > >Avi, Marcelo, maybe you can carry this in kvm/linux-next as a temporary
> > >measure so that linux-next builds?
> > >
> >
> > I'm not happy about that as a workflow, but since you guys have an
> > immediate problem I guess we can do that.
>
> I'm rather unhappy about this workflow - we've got quite a few
> apic bits in the x86 tree this cycle as well and need extra
> external interaction, not.
>
> Which KVM tree commit caused this, could someone please give a
> lkml link or quote it here? It's not referenced in the fix patch
> either.
>
> Thanks,
>
> Ingo
This tree (kvm.git next):
http://git.kernel.org/?p=virt/kvm/kvm.git;a=shortlog;h=refs/heads/next
Introduced by this commit:
http://git.kernel.org/?p=virt/kvm/kvm.git;a=commit;h=ab9cf4996bb989983e73da894b8dd0239aa2c3c2
next prev parent reply other threads:[~2012-07-06 11:32 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-01 15:05 [PATCH] apic: fix kvm build on UP without IOAPIC Michael S. Tsirkin
2012-07-01 16:23 ` Randy Dunlap
2012-07-01 17:10 ` H. Peter Anvin
2012-07-06 11:13 ` Ingo Molnar
2012-07-06 11:32 ` Marcelo Tosatti [this message]
2012-07-06 14:12 ` Ingo Molnar
2012-07-08 20:56 ` Michael S. Tsirkin
2012-07-09 9:24 ` Ingo Molnar
2012-07-03 18:55 ` Marcelo Tosatti
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