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Re: [Qemu-devel] [PATCH] vfio/pci: Improve extended capability comments,

From: Peter Xu
Subject: Re: [Qemu-devel] [PATCH] vfio/pci: Improve extended capability comments, skip masked caps
Date: Wed, 22 Feb 2017 12:10:55 +0800
User-agent: Mutt/1.5.24 (2015-08-30)

On Tue, Feb 21, 2017 at 08:54:31PM -0700, Alex Williamson wrote:


> I prefer the existing code.  I don't really see why you consider it a
> hack.  I think it's pretty elegant that we can ignore the header
> through the course of iterating through the capabilities, that we drop
> other masked capabilities out of the chain, and that we can so easily
> and transparently insert a zero ID at the end to serve the dual purpose
> of replacing the temporary ID and nullifying the list if nothing was
> added.  The 0xffff capability ID is a perfectly safe assumption, not
> only are we ridiculously far from allocating that ID, but it's arguably
> a reserved value due to its use in the root complex register block.  I
> also don't see any evidence that it's error prone, the entire point is
> that we can arbitrarily skip capability IDs in the body of the loop and
> the result is a correct, minimal capability chain.  OTOH, leaving
> masked capabilities in the chain with an arbitrary version number seems
> messy.

I see. Then please also pick this one:

Tested-by: Peter Xu <address@hidden>

> The real question is why are you sneaking the virtual channel
> capability into the list of masked capabilities?  Thanks,

Oooops. I should remove that line. It's for my testing purpose (I need
to "fake" a device that with 0x100 masked to test my patch, while my
SD card reader did has this VC cap at 0x100 :-). Since we now have a
choice already, please just ignore that line along with the whole
patch. ;)


-- peterx

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