Messages in this thread | | | Date | Fri, 22 Feb 2008 12:18:04 +0100 | From | "Joerg Roedel" <> | Subject | Re: [PATCH] X86: don't print a warning when MTRR are blank and running in KVM |
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On Thu, Feb 21, 2008 at 11:54:00AM -0800, Yinghai Lu wrote: > On Thu, Feb 21, 2008 at 6:50 AM, Joerg Roedel <joerg.roedel@amd.com> wrote: > > Inside a KVM virtual machine the MTRRs are usually blank. This confuses Linux > > and causes a warning message at boot. This patch removes that warning message > > when running Linux as a KVM guest. > > > > Signed-off-by: Joerg Roedel <joerg.roedel@amd.com> > > --- > > arch/x86/kernel/cpu/mtrr/main.c | 7 +++++-- > > 1 files changed, 5 insertions(+), 2 deletions(-) > > > > diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c > > index b6e136f..47e624c 100644 > > --- a/arch/x86/kernel/cpu/mtrr/main.c > > +++ b/arch/x86/kernel/cpu/mtrr/main.c > > @@ -43,6 +43,7 @@ > > #include <asm/uaccess.h> > > #include <asm/processor.h> > > #include <asm/msr.h> > > +#include <asm/kvm_para.h> > > #include "mtrr.h" > > > > u32 num_var_ranges = 0; > > @@ -687,12 +688,14 @@ int __init mtrr_trim_uncached_memory(unsigned long end_pfn) > > } > > > > /* kvm/qemu doesn't have mtrr set right, don't trim them all */ > > - if (!highest_pfn) { > > + if (!highest_pfn && !kvm_para_available()) { > > printk(KERN_WARNING "WARNING: strange, CPU MTRRs all blank?\n"); > > WARN_ON(1); > > - return 0; > > } > > > > + if (!highest_pfn) > > + return 0; > > + > > if (highest_pfn < end_pfn) { > > printk(KERN_WARNING "WARNING: BIOS bug: CPU MTRRs don't cover" > > " all of memory, losing %luMB of RAM.\n", > > -- > > 1.5.3.7 > > > > Doest that WARN_ON(1) hurt?
Yes. It inidicates a problem where there isn't one. In a virtual machine MTRRs make absolutly no sense and so they should all be blank there.
Joerg
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