Re: ANNOUNCE: Xen Transcendent Memory support now in stock Ubuntu and Fedora guest kernels

[Konrad Rzeszutek Wilk <konrad@kernel.org>]

On Tue, Nov 27, 2012 at 01:24:33PM -0800, Dan Magenheimer wrote:
> FYI, it has come to my attention that both the kernel in the
> recently-released Ubuntu 12.10 (aka Quantal Quetzal) and the
> kernel in Fedora 17 (after yum-update to a 3.5-or-later kernel)
> are fully configured to support Transcendent Memory ("tmem").

Woohoo!
> Oracle's "UEK2" kernel has also had tmem support since its release
> in early 2012.
> 
> To enable tmem support in Xen, it is necessary to specify
> a Xen boot parameter ("tmem").  Specifying "dom0_mem="

There are some extra ones too - tmem_compress tmem_dedup right?

> and disabling dom0 autoballooning in the toolstack is also
> highly recommended.  Then tmem must be explicitly enabled in
> any tmem-capable guest kernel by specifying a boot parameter
> (also "tmem") in each guest grub.conf.  Note that use of
> tmem in dom0 is not recommended, so "tmem" should not be
> provided as a dom0 boot parameter.
> 
> I'll try to write up a more complete current HOW-TO soon
> since much of the Xen tmem documentation floating around
> the web is a bit outdated.
> 
> Note that some security issues were reported in the
> Xen hypervisor tmem implementation last summer.  Please
> ensure your hypervisor is updated to patch XSA-15 before
> enabling tmem on a Xen machine exposed to the internet!
> 
> Thanks,
> Dan
> 
> P.S. If you build your own Linux guest kernels, a 3.5-or-later
> kernel is required built with the following config variables:
> 
> CONFIG_FRONTSWAP=y
> CONFIG_CLEANCACHE=y
> CONFIG_XEN_TMEM=y
> CONFIG_XEN_SELFBALLOONING=y
> 
> 
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