On Sat, Jan 7, 2012 at 7:36 PM, Pandu Poluan <pa...@poluan.info> wrote: > On Jan 8, 2012 12:43 AM, "Michael Mol" <mike...@gmail.com> wrote: >> On Sat, Jan 7, 2012 at 11:35 AM, Pandu Poluan <pa...@poluan.info> wrote: >> > On Jan 7, 2012 8:44 PM, "victor romanchuk" <r...@persimplex.net> wrote: >> >> >> >> Konstantinos Agouros wrote, at 01/07/2012 03:51 PM: >> >> > since xen got into the mainstream kernel the way to go is to use >> >> > gentoo-sources for dom0 and the domUs. However the blktap modules are >> >> > not >> >> > there. Is there any way to get this to work? >> >> >> >> blktap drivers were excluded from kernel mainline since 3.x, these two >> >> threads >> >> from xen-users mailing list might put some light in that context: >> >> >> >> >> >> >> >> http://old-list-archives.xen.org/archives/html/xen-users/2011-07/msg00637.html >> >> >> >> >> >> http://old-list-archives.xen.org/archives/html/xen-users/2011-10/msg00065.html >> >> >> >> the latest sys-kernel/xen-sources containing working blktap (not >> >> blktap2) >> >> is >> >> 2.6.38 (this is buggy from my point of view; i'm still sitting on >> >> 2.6.34-r5 for >> >> production installations) >> >> >> > >> > Can someone shed a light on the importance of blktap, i.e., why one >> > would >> > want to use it when -- as someone explained in the first email thread >> > you >> > gave -- blkfront+blkend is enough for paravirtualization? >> >> Reading through the linked threads, it sounds like the benefit stems >> from being able to shim things in between the front and back ends. >> >> You might want that for any number of reasons: >> * a block encryption layer >> * a metering layer >> * a read/write masking layer >> * an intercept to have the block device exist on (or be mirrored to) >> on another system. >> >> etc. >> > > Ah yes, of course. > > One of the threads also mentioned that blktap might be better implemented in > userspace.
Well, there's that, too. For a while, there's been a long push in Linux to get anything that could remotely reasonably be done in userspace out of kernelspace. -- :wq
