Karmic Configuration Updates

[Andy Whitcroft]

Following on from the config changes already committed, there were a number
of other recommendations which were not implementable for one reason or
another.  There are a number of options which require further discussions.
For each I have tried to enumerate the issues and provide a recommendation.

STAGING: a couple of the options we have chosen to enable are not enabled
on all platforms as STAGING is not enabled for armel or lpia.  Do we want
to enable STAGING on all supported platform.  I feel we should be more
consistent with this one across the distro kernels.  Affected options:

	 CONFIG_POHMELFS_CRYPTO
	 CONFIG_VIDEO_GO7007

Recommendation: CONFIG_STAGING=y

LZMA: it was generally seen as a good thing that we enable LZMA.
Some config options were selected for enabling, however a number of
them were mutually exclusive with the options we already had enabled.
One was the option for switching the kernel to LZMA compression.
It is not clear that this is an appropriate change as the decompress
times for LZMA are pretty high compared to gzip (the current default),
something around 2x[1].  We also have already reduced our compression in
order to speed up update-initramfs -u [2].  It is therefore not clear
we can or should blindly change these without at least some testing.
Until we have those results we should enable support for LZMA format
initramfs files (CONFIG_RD_LZMA) without changing how we compress things.
It is likely we should spawn a new BluePrint for the investigations on
which compression algorithm is appropriate for the various platforms,
likely for the LL cycle.

 [1] http://tukaani.org/lzma/benchmarks
 [2] http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=470869

Recommendation: CONFIG_RD_LZMA=y

PCI_IOV: this option enables support for a PCI mode in which capable
devices can offer virtual versions of themselves.  These are generally
used to share physical cards between virtual instances at near full
performance.  This is a bigger server feature currently.  As there are
few devices which offer it, and it only applies to those cards it seems
reasonble to enable it.

Recommendation: CONFIG_PCI_IOV=y

PCI_STUB: this option allows you to reserve a PCI device so that it can
be handed off wholesale to a virtual guest operating systems.  This is
a bigger server feature currently.  As it can be a module and would be
an opt-in option it seem reasonable to enable it.

Recommendation: CONFIG_PCI_STUB=m

I would propose to produce a second patch set including these changes
shortly.

Comments?

-apw