Re: MSR support for x86

H. Peter Anvin (
Fri, 28 Feb 1997 16:10:51 -0800 (PST)

> I should think you would want it to be crw-r--r--, so that anybody can see
> what they are running on. Perhaps the /dev/msr code should double check
> that root is doing the write, so even if somebody can get past the VFS, they
> still can't fry your CPU.
> Also, what will this do on a SMP system? Just die, only set the first CPU,
> set all of them?

Yes, there need to be something reasonable. I do *not* think it is
reasonable for random processes to even read the special registers --
on some CPUs that could potentially give away dangerous information.

I think /dev/msr on a multiprocessor should read the CPU the process
is running on.