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Message-Id: <1179876460.20705.157.camel@localhost.localdomain>
Date: Wed, 23 May 2007 09:27:40 +1000
From: Rusty Russell <rusty@...tcorp.com.au>
To: Matt Mackall <mpm@...enic.com>
Cc: linux-kernel@...r.kernel.org, akpm@...ux-foundation.org
Subject: Re: lguest broken in 2.6.22-rc1-mm1
On Tue, 2007-05-22 at 17:38 -0500, Matt Mackall wrote:
> [ 0.120007] EIP is at resync_sc_freq+0x4b/0x56
Hi Matt,
Thanks for the report! Andrew should have these two patches queued,
but here they are again:
If you set tsc_disable (eg "notsc" on cmdline), sched-clock.c gives a
divide by zero on boot.
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
---
arch/i386/kernel/sched-clock.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
===================================================================
--- a/arch/i386/kernel/sched-clock.c
+++ b/arch/i386/kernel/sched-clock.c
@@ -103,7 +103,7 @@ static void resync_sc_freq(struct sc_dat
static void resync_sc_freq(struct sc_data *sc, unsigned int newfreq)
{
sc->sync_base = jiffies;
- if (!cpu_has_tsc) {
+ if (!cpu_has_tsc || tsc_disable) {
sc->unstable = 1;
return;
}
Lguest guests don't use the TSC, and so we must disable it otherwise
sched-clock.c barfs.
Also, we no longer need to explicitly set the PGE feature bit:
cpu_detect->cpuid->lguest_cpuid does that for us now that cpu_detect
uses paravirt_ops (IIRC it used to do a direct cpuid from assembler).
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
---
drivers/lguest/lguest.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
===================================================================
--- a/drivers/lguest/lguest.c
+++ b/drivers/lguest/lguest.c
@@ -504,10 +504,10 @@ __init void lguest_init(void *boot)
reserve_top_address(lguest_data.reserve_mem);
cpu_detect(&new_cpu_data);
- /* Need this before paging_init. */
- set_bit(X86_FEATURE_PGE, new_cpu_data.x86_capability);
/* Math is always hard! */
new_cpu_data.hard_math = 1;
+
+ tsc_disable = 1;
#ifdef CONFIG_X86_MCE
mce_disabled = 1;
-
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