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Re: [Xen-devel] [PATCH 0 of 4] aio event fd support to blktap2

To: Daniel Stodden <daniel.stodden@xxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH 0 of 4] aio event fd support to blktap2
From: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
Date: Fri, 29 Jan 2010 10:34:44 +0000
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On Thu, 2010-01-28 at 22:37 +0000, Daniel Stodden wrote:
>   - Does a runtime kernel version check. I guess this code will
>     need additional cpp magic on BSDs. 

I guess BSD will need cpp magic regardless of the kernel version check
since it will have a different interface altogether. But for the Linux
version can we not just try eventfd(), check for -ENOSYS and fall back
to the old way if necessary, instead of hardcoding the kernel version?

I suppose eventfd is an unlikely candidate for backporting to anything
older but in general IMHO it's preferable to check for the actual
functionality you want to use rather than hardcoding version numbers
etc.

Ian.



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