Re: [PATCH 1/2] x86/mce: Only restart instruction after machinecheck recovery if it is safe

From: Borislav Petkov
Date: Mon May 14 2012 - 13:17:14 EST


On Mon, May 14, 2012 at 04:16:05PM +0000, Luck, Tony wrote:
> >> + int restartable;
> >
> > Is it me or does this look like a flag, or a bitfield? Instead of
> > wasting a whole integer for a single bit of information.
>
> I could make it "int flags;" and "#define MCE_INFO_RESTARTABLE 1"
> to make it clear that we have lots more bits available for special
> cases?

I was wondering about that but don't have any other flags/use cases.
Well, we can always change it later if needed.

> > It will probably end up the same size though due to compiler padding
> > since this struct is currently 4 + 2*8 byte without the ->restartable
> > thing.
>
> Yup - we can't save any memory (unless we introduce more complexity to
> the code ... low PAGE_SHIFT bits of the "paddr" field are simply thrown
> away ... so we could allocate a bit there ... but I don't think that
> the resulting ugliness is worth the memory savings).

Agreed, that would be too ugly for no reason :-)

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