linux-kernel - Re: [RFC PATCH 2/3] Implement sysfs based cpuinfo for x86 cpus.

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Date:   Fri, 9 Jun 2017 17:22:19 +0200
From:   Brice Goglin <Brice.Goglin@...ia.fr>
To:     Thomas Renninger <trenn@...e.de>,
        Greg KH <gregkh@...uxfoundation.org>
Cc:     Felix Schnizlein <FSchnizlein@...e.com>, yanmin.zhang@...el.com,
        linux-kernel@...r.kernel.org, x86@...r.kernel.org
Subject: Re: [RFC PATCH 2/3] Implement sysfs based cpuinfo for x86 cpus.



Le 09/06/2017 15:28, Thomas Renninger a écrit :
> On Thursday, June 08, 2017 08:24:01 PM Greg KH wrote:
>> On Thu, Jun 08, 2017 at 06:56:14PM +0200, Felix Schnizlein wrote:
>>> ---
>>>  arch/x86/kernel/Makefile        |   1 +
>>>  arch/x86/kernel/cpuinfo_sysfs.c | 166 
> ++++++++++++++++++++++++++++++++++++++++
>>>  drivers/base/cpuinfo.c          |   4 -
>>>  3 files changed, 167 insertions(+), 4 deletions(-)
>>>  create mode 100644 arch/x86/kernel/cpuinfo_sysfs.c
>>>
>> When you add new sysfs entries, you have to also add new
>> Documentation/ABI/ entries.
> This one seem to be rather unmaintained?
> There even is:
> Documentation/ABI/stable/sysfs-devices-system-cpu
> this patchset would have to add:
> Documentation/ABI/stable/sysfs-devices-system-cpu-cpuinfo
> then.
>
> But:
> Documentation/ABI/stable/sysfs-devices-system-cpu
> describes
> /sys/devices/system/cpu/dscr_default
> and
> /sys/devices/system/cpu/cpu[0-9]+/dscr
>
> which I have never seen.
>
> Much more important values in there like:
> /sys/devices/system/cpu/topology
> /sys/devices/system/cpu/microcode
> /sys/devices/system/cpu/cpuidle
> /sys/devices/system/cpu/cpufreq
> /sys/devices/system/cpu/{online,offline}

They are documented in
Documentation/ABI/testing/sysfs-devices-system-cpu (which doesn't
contain dscr)

Brice


>
> are not described there at all.
>
> I wonder whether .../cpu/dscr_default still exists in the
> kernel, a quick grep did not reveal anything.
> A
> Source:
> tag would be a nice non-optional addition in the README.
>
> We can also send definitions for topology/microcode/cache/..
> to catch up a bit there again, not sure that makes much sense.
>
> Be aware that the output of /proc/cpuinfo is rather arbitrary
> depending on architecure and some build options.
>
>       Thomas