hi, all. how can I write msr while in domain0? thanks in advance:)

hi, all. how can I write msr while in domain0? thanks in advance:)

[danielsong]

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I want to write 0x2a msr(concerning power-on configuration);
currently I rebuild the kernel adding support for /dev/cpu/msr0.
so I just access the file through the file.

the problem is that:It seems that I can't write a value into the 0x2a
msr(also 0x10-tsc msr).

after searching in xensource web, I found that we can modify the
emulate_privileged_op() in xen/arch/x86/traps.c
but when add a printk sentence at the beginning of the
emulate_privileged_op()
I didn't get the output using dmesg | tail.

it seems that the wrmsr didn't get into the emulate_privileged_op() ?
the rdmsr operation is the same as wrmsr:-)


thank you.


-- 
Best Regrads,
DanielSong

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Re: hi, all. how can I write msr while in domain0? thanks in advance:)

[Keir Fraser]

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On 26/4/07 09:32, "danielsong" <sjtusongyi@gmail.com> wrote:

> after searching in xensource web, I found that we can modify the
> emulate_privileged_op() in xen/arch/x86/traps.c
> but when add a printk sentence at the beginning of the emulate_privileged_op()
> I didn't get the output using dmesg | tail.
>  
> it seems that the wrmsr didn't get into the emulate_privileged_op() ?
> the rdmsr operation is the same as wrmsr:-)


That¹s absolutely the function where RDMSR/WRMSR ends up. Are you looking in
the right place for the Xen output? VGA is taken over by domain0 by default
when it starts to boot. Have you looked at Œxm dmesg¹ output?

 -- Keir


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Re: hi, all. how can I write msr while in domain0? thanks in advance:)

[Luke S. Crawford]

On Thu, 26 Apr 2007, danielsong wrote:
> after searching in xensource web, I found that we can modify the
> emulate_privileged_op() in xen/arch/x86/traps.c
> but when add a printk sentence at the beginning of the
> emulate_privileged_op()
> I didn't get the output using dmesg | tail.


I'm pretty sure you want

xm dmesg

(run it from within the Dom0 as root)

dmesg just gives you the linux kernel log, while it sounds like you  want 
the Xen kernel log.