Re: [Xen-devel] [PATCH 4/4] xen/arm: correctly handle an empty array of platform descs.

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Wed, 2013-05-15 at 13:19 +0100, Jan Beulich wrote:
> >>> On 15.05.13 at 11:47, Ian Campbell <ian.campbell@xxxxxxxxxx> wrote:
> 
> >> As Linux doesn't play with symbol visibility, we're really alone
> >> having this problem, and hence indeed need to go through and
> >> audit all places where the potential for empty ranges exists.
> > 
> > The comment says "Results in more efficient PIC code (no indirections
> > through GOT or PLT).", how much PIC code is there in the hypervisor
> > anyway?
> 
> All x86-64 code has been built with -fpic from the beginning. That
> likely was the easiest (and possibly the only available) solution to
> not being able to use -mcmodel=kernel.

I should probably investigate not doing this for ARM, where we don't use
fpic, then!

> >> But you said "<" instead of "!=" didn't have any surprising side
> >> effects, so quite likely we won't need much code to change.
> > 
> > "<" fails because it does process the (non-existent) first entry in the
> > array. This happened to be "safe" in the case I saw but it wouldn't be
> > in general.
> 
> Okay, I misread one of your earlier responses then. Did you do
> the necessary auditing already, or should I put this on my todo
> list?

I haven't done an audit. I put a very quicly grepped list in a previous
mail but it is surely incomplete.

Ian.



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