Date: Sat, 17 May 2008 20:10:41 +0300 From: Andriy Gapon <avg@icyb.net.ua> To: Rui Paulo <rpaulo@FreeBSD.org> Cc: freebsd-hackers@FreeBSD.org Subject: Re: rdmsr from userspace Message-ID: <482F1191.70709@icyb.net.ua> In-Reply-To: <482EFBA0.30107@FreeBSD.org> References: <482E93C0.4070802@icyb.net.ua> <482EFBA0.30107@FreeBSD.org>
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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? -- Andriy Gapon
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