Re: [PATCH] [mcelog] Start using the new sysfs tunables location

["Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>]

On 09/06/2012 12:39 AM, Tony Luck wrote:
> On Wed, Sep 5, 2012 at 11:47 AM, Andi Kleen <andi@firstfloor.org> wrote:
>> On Wed, Sep 05, 2012 at 04:02:37PM +0530, Naveen N. Rao wrote:
>>> All the current mce tunables are now available under
>>> /sys/devices/system/machinecheck. Start using this new location, but fall back
>>> to the older per-cpu location so that we continue working with older kernels.
>>
>> Who did that change in the kernel?
>>
>> That breaks Linus rule that the kernel should not break userland.
>> Kernel needs to fix that.
>
> The change is still under discussion. Stage one is to add the new global
> pathnames in addition to keeping the old per-cpu ones. Also fix all utilities
> (just mcelog(8) as far as we know) to prefer the new paths.
>
> After some time[1] ... delete the old paths. This is allowable under Linus'
> modified edict that you can change ABI "if nobody complains". If we wait
> long enough that the new mcelog is widely deployed, then nobody should
> complain.
>
> -Tony
>
> [1] several years - not just a kernel release or two.
>

Tony,
Thanks for clarifying. I should have mentioned in the patch description 
that this is indeed subject to the original patch making it into the kernel.

On a related topic. I recently noticed that we don't have an entry for 
machinecheck in Documentation/ABI/. Should we add an entry in there? We 
could perhaps add the existing entries under obsolete/ and the new 
location under testing/?


- Naveen