Re: [Xen-devel] RFC: blktap3

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2012-08-09 at 15:03 +0100, Thanos Makatos wrote:
> Hi,
> 
>  
> 
> Iâd like to introduce blktap3: essentially blktap2 without the need of
> blkback. This has been developed by Santosh Jodh, and Iâll maintain
> it.
> 
>  
> 
> In this patch, blktap2 binaries are suffixed with â2â, so itâs not yet
> possible to use it along with blktap3.

I'll take a proper look at this when I get back from vacation but just a
few quick first comments:

I don't think renaming blktap2 is going to fly. For better or worse
blktap2 uses the names it uses and people (and xend) use them with those
names, so I think blktap3 needs to avoid the conflict by adding "3" as
appropriate.

I noticed that the README looks pretty blktap1 specific and references
xm etc. It would be nice to decruft the tree as part of this transition
rather than carrying across obsolete and out of date components from
blktap1 & 2 into the blktap3 stack. I bet there is other stuff which is
no longer used, e.g. the libaio-compat.h -- does the need for that still
exist or is libaio now up to date in distros (it reference 2.6.21, which
is quite a while ago now). I expect you also want to ditch
linux-blktap.h -- it looks like ioctl definitions for talking to the
(now non-existent) kernel driver. It'd be good to strip all this sort of
thing out before people start reviewing in depth -- there's not much
point in reviewing stuff which should just be removed and the patch is
big enough as is.

On a similar note if there are plugin modules which are not often used
in normal configurations perhaps they could be omitted from the initial
upstreaming? (I don't know what all of block-* etc are,  but maybe some
of them are not really used in practice?)


Ian.


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