Date: Sat, 17 May 2008 13:32:28 -0400 From: Mike Meyer <mwm-keyword-freebsdhackers2.e313df@mired.org> To: Rui Paulo <rpaulo@FreeBSD.org> Cc: freebsd-hackers@FreeBSD.org, Andriy Gapon <avg@icyb.net.ua> Subject: Re: rdmsr from userspace Message-ID: <20080517133228.02c9ea5c@bhuda.mired.org> In-Reply-To: <482F1529.5080409@FreeBSD.org> References: <482E93C0.4070802@icyb.net.ua> <482EFBA0.30107@FreeBSD.org> <482F1191.70709@icyb.net.ua> <482F1529.5080409@FreeBSD.org>
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On Sat, 17 May 2008 18:26:01 +0100
Rui Paulo <rpaulo@FreeBSD.org> wrote:
> Andriy Gapon wrote:
> > on 17/05/2008 18:37 Rui Paulo said the following:
> >> Andriy Gapon wrote:
> >>>
> >>> It seems that rdmsr instruction can be executed only at the highest
> >>> privilege level and thus is not permitted from userland. Maybe we
> >>> should provide something like Linux /dev/cpu/msr?
> >>> I don't like interface of that device, I think that ioctl approach
> >>> would be preferable in this case.
> >>> Something like create /dev/cpuN and allow some ioctls on it:
> >>> ioctl(cpu_fd, CPU_RDMSR, arg).
> >>> What do you think?
> >>>
> >>
> >> While I think this (devcpu) is good for testing and development, I
> >> prefer having a device driver to handle that specific MSR than a
> >> generic /dev/cpuN where you can issue MSRs.
> >> Both for security and reliability reasons.
> >
> > What about /dev/pci, /dev/io? Aren't they a precedent?
>
> They are, but, IMHO, we should no longer continue to create this type of
> interfaces.
Ok, in relation to the question I asked about sysctl's vs. /dev/* -
why not?
<mike
--
Mike Meyer <mwm@mired.org> http://www.mired.org/consulting.html
Independent Network/Unix/Perforce consultant, email for more information.
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