Messages in this thread | | | Date | Tue, 18 Nov 2014 01:31:38 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH v3 13/13] perf/x86: add syfs entry to disable HT bug workaround |
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On Tue, 18 Nov 2014, Borislav Petkov wrote: > On Tue, Nov 18, 2014 at 12:38:14AM +0100, Thomas Gleixner wrote: > > Well a bitmask is a pretty indescriptive item as well. Putting my user > > hat on: Where is the documentation for the bits? > > $ cat /sys/devices/system/cpu/bugs > 0xXXXXXX - currently enabled workarounds are the set bits. > bit 0: workaround for bug#blabla > bit 1: workaround for bug#1 > bit 2: workaround for bug#2; remember to do <bla> before disabling workaround > ... > bits n-63 are reserved, cannot be set and RAZ.
You sure that 64 are enough?
You need to create stable but numbers, i.e. each bug gets a fixed but number whethr it affects the machine or not. Otherwise you will drive admins completely nuts.
> This will be issued when user cats the sysfs file.
That might work as well, though you want that to be:
/sys/devices/system/cpu/bugs/
/sys/devices/system/cpu/bugs/status
/sys/devices/system/cpu/bugs/enable_workaround
/sys/devices/system/cpu/bugs/disable_workaround
The latter two take a bit number rather than a magic mask.
So while it looks less effort to implement and extend in the first place I think, that a bit of infrastructure work will make the explicit scheme I proposed before a no brainer to maintain and extend, but I cannot judge what's more intuitive to use.
Thanks,
tglx
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