Re: [PATCH 1/4] mce: Slim up struct mce

[Ingo Molnar <mingo@elte.hu>]

* Luck, Tony <tony.luck@intel.com> wrote:

> > Drop unused ->apicid, make ->socketid __u16 since it is 
> > copied from struct cpuinfo_86.phys_proc_id, reorder members 
> > and adjust padding so that it remains packed and on a 
> > 64-byte boundary.
> 
> This structure is user visible via /dev/mcelog.  The mcelog(8) 
> daemon has been coded to cope with extra fields being added to 
> the end of the structure (an old daemon that doesn't know what 
> they are will just skip over them). But things will break if 
> you change the offsets of any fields that it does know about.

Please separate out a 'struct mce_legacy' data type that 
contains the /dev/mcelog format, and use it in the place that 
outputs to /dev/mcelog (and convert from 'struct mce' to 'struct 
mce_legacy' and back when interacting with /dev/mcelog).

This keeps 'struct mce' kernel internal and flexible. A pure 
kernel internal structure should never have been exported like 
this to begin with, doing that results in problems like this.

Thanks,

	Ingo