linux-kernel - Current git kernel reboots early durning boot

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Date:	Mon, 9 Sep 2013 13:18:40 +0200
From:	Markus Trippelsdorf <markus@...ppelsdorf.de>
To:	linux-kernel@...r.kernel.org
Subject: Current git kernel reboots early durning boot

I've hit an odd issue on the current git tree. When I build a kernel
with my attached config and a very simple local patch (also attached), I
get a resulting kernel that just reboots my machine very early during
boot. When I try to boot the kernel under qemu, qemu just spins forever
without printing anything to the console. This happens when I build with
gcc-4.8.1 and gold (linker). When I drop the local kernel patch or
switch to the bfd linker, the kernel boots normally...

Any ideas what might be going on?
Can anybody else reproduce the issue?

Here's the simple local patch I'm using. (It silences some unimportant
kvm warnings.)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index ca645a0..8822cd2 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -415,7 +415,7 @@ struct kvm {
 #define kvm_debug(fmt, ...) \
 	pr_debug("kvm [%i]: " fmt, task_pid_nr(current), ## __VA_ARGS__)
 #define kvm_pr_unimpl(fmt, ...) \
-	pr_err_ratelimited("kvm [%i]: " fmt, \
+	pr_debug_ratelimited("kvm [%i]: " fmt, \
 			   task_tgid_nr(current), ## __VA_ARGS__)

 /* The guest did something we don't support. */

For qemu testing I use:
 % qemu-system-x86_64 -enable-kvm -net nic,vlan=0,model=virtio -net user -fsdev local,security_model=none,id=root,path=/ -device virtio-9p-pci,id=root,fsdev=root,mount_tag=/dev/root -m 512 -smp 2 -kernel /usr/src/linux/arch/x86/boot/bzImage -nographic -append "init=/bin/zsh root=/dev/root console=ttyS0 kgdboc=ttyS0 rootflags=rw,trans=virtio rootfstype=9p ip=dhcp"

-- 
Markus

View attachment "kvm_kernel.patch" of type "text/x-diff" (504 bytes)

View attachment "config" of type "text/plain" (68090 bytes)