On Tue, Feb 24, 2009 at 10:40:57PM +1300, Michael Kerrisk wrote: > > .\" Some sentences copied from comment in arch/x86/kernel/msr.c > > .TH MSR 7 2009-02-22 "Linux" "Linux Programmer's Manual" > > .SH NAME > > msr \- x86 CPU MSR access device > > .SH DESCRIPTION > > .I /dev/cpu/CPUNUM/msr > > allows to read and write the model specific registers (MSRs) of an x86 CPU. > > .I CPUNUM > > is the number of the cpu to access as listed in > > .I /proc/cpuinfo. > > The register access is done by opening the file and seeking to the MSR > > number > > Could you clarify "seek to the MSR number" == does that mean seek to > offset (MSR_number * 8) or something like that? No it means seek to MSR number. Yes the semantics are a little weird. > > > as offset in the file and then read or write in chunks of 8 bytes. > > A larger size than 8 bytes means multiple reads or writes of the > > same register. > > What are the semantics of reading the same register multiple times? > Is a read non-destructive? Do the multiple reads always get the same > value? It depends on the hardware. A typical x86 CPU has hundreds of different MSRs. Typically they're non destructive, but some might still change. I intentionally didn't try to cover that but just added references (although those could be probably also extended) BTW what I also forgot was a note that it's root only. Please just edit it yourself. I assume you'll be doing that anyways. -Andi -- ak@xxxxxxxxxxxxxxx -- Speaking for myself only. -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
