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. O< ascii ribbon campaign - stop html mail - www.asciiribbon.org
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