Re: [Xen-devel] blktap2 header consistency between userspace and kernel space

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Tue, Apr 23, 2013 at 04:08:08PM +0200, Sylvain Munaut wrote:
> Hi,
> 
> > Is this something related to blktap2 vs. blktap2.5 ?
> >
> > IIRC blktap2.5 userland requires blktap2.5 kernel modules..
> 
> Honestly ... I'm not sure. Where are the reference/authoritative tree
> for blktap2 and 2.5, both kernel and userspace ?
> 
> Since I took those headers from the debian repo, blktap-utils and
> blktap-dkms, I would have expected them to be compatible ...
> 

Ok so this all is very confusing.. but I'll try to explain it:

for userspace blktap tools:

        - blktap2: it's in Xen hypervisor sources, so the latest version is in 
xen-unstable (xen.git master branch).

        - blktap2.5: This is a blktap2 fork (and most "recent" version with 
additional features) that's being used in XenServer/XCP and with xapi toolstack 
in general: https://github.com/xen-org/blktap .


for blktap kernel modules:

        - blktap2: I think Suse/Novell is maintaining these patches in their 
classic "xenlinux" kernels, and they're also in Jeremy's (now abandoned) 
xen.git Linux dom0 kernel tree based on Linux 2.6.32. These patches newer went 
into upstream Linux, and probably never will. There are also various forward- 
and back-ports of these to some newer Linux 3.x kernels. These patches also 
exist in xen.org linux-2.6.18-xen classic xenlinux tree. I'm not aware of any 
"official" kernel tree with up-to-date blktap2 patches for recent Linux kernels.

        - blktap2.5: These drivers can be found from XenServer/XCP 2.6.32 
classic xenlinux dom0 kernel trees, and also from dstodden's (now abandoned) 
git repo at 
http://xenbits.xen.org/gitweb/?p=people/dstodden/linux.git;a=summary and 
http://xenbits.xen.org/gitweb/?p=people/dstodden/blktap-dkms.git;a=summary . 
dstodden switched jobs, so those are unmaintained repos. CentOS6 Linux 3.4 Xen 
dom0 kernel also has the blktap2.5 patches/drivers included.


If I remembered something wrong, or pointed to wrong places, or forgot 
something, please correct me :)

And then the good news: blktap3 is in the works, see patches on xen-devel 
mailinglist, and it won't need any blktap kernel driver! It's purely an 
userspace solution, with an active maintainer/developer.

-- Pasi


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