Messages in this thread | | | Date | Sun, 25 Mar 2018 16:12:42 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH v3 1/2] x86, msr: allow rdmsr_safe_on_cpu() to schedule |
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On Sat, Mar 24, 2018 at 07:29:48AM -0700, Eric Dumazet wrote: > It is named gsysd, "Google System Tool", a daemon+cli that is run > on all machines in production to provide a generic interface > for interacting with the system hardware.
So I'm wondering if poking at the hardware like that is a really optimal design. Maybe it would be cleaner if the OS would provide properly abstracted sysfs interfaces instead of raw MSRs. For a couple of reasons:
* different vendors have different MSR ranges giving the same info so instead of differentiating that in your daemon, we can do that nicely in the kernel.
* exposing raw MSRs instead of having clearly defined sysfs files is always a pain when a new CPU decides to change those MSRs. Hiding that change in the OS is always easier.
* periodically polling MSRs which don't change that often is, of course, wasting power and so reading a cached result is leaner.
* <another reason which I'll think of after hitting send... :\ >
In general, we should've never have had exposed that raw MSR access but it is too late now - that ship has sailed. We can still try to design new interfaces more cleanly, though.
-- Regards/Gruss, Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
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