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

[Borislav Petkov <bp@amd64.org>]

On Sat, Mar 03, 2012 at 08:37:26AM +0100, Ingo Molnar wrote:
> 
> * 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).

Either that or I'll save my patch for when we remove /dev/mcelog
altogether.

> 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.

Ho-hum.

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Boris.

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