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Re: [Xen-devel] [patch] make evtchn_upcall_pending arch-specific type

On 13 Jun 2006, at 21:02, Hollis Blanchard wrote:

You'll notice I added an alignment attribute to that field because it
really really needs to be aligned for us. This has only been
build-tested on x86!

If it's acceptable, please apply.

Hide evtchn_upcall_pending test-and-set accesses behind a wrapper.
Signed-off-by: Hollis Blanchard <hollisb@xxxxxxxxxx>

It would probably be better to move the TAS of the upcall_pending flag into evtchn_notify(). Avoids expanding the arch-specific interface further.

We have avoided adding gcc extensions to core public header files as it prevents easy use of the header files by some other projects (e.g., solaris port, I believe). You should instead add a suitable BUILD_BUG_ON() in arch/ppc -- in any case, if field offsets change in future you break backward compatibility, even if new field alignment does happen to still be 'okay' in that one case.

 -- Keir

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