Date: Sat, 17 May 2008 18:26:01 +0100 From: Rui Paulo <rpaulo@FreeBSD.org> To: Andriy Gapon <avg@icyb.net.ua> Cc: freebsd-hackers@FreeBSD.org Subject: Re: rdmsr from userspace Message-ID: <482F1529.5080409@FreeBSD.org> In-Reply-To: <482F1191.70709@icyb.net.ua> References: <482E93C0.4070802@icyb.net.ua> <482EFBA0.30107@FreeBSD.org> <482F1191.70709@icyb.net.ua>
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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. Regards, -- Rui Paulo
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