Re: Where do we stand with the Xen patches?

From: Jeremy Fitzhardinge
Date: Sun May 17 2009 - 21:55:01 EST


devzero@xxxxxx wrote:
or is maintaining two different kernel packages a problem?

Yes, distros hate the proliferation of kernel packages with different config options, partly because of the combinatorial explosion (32 vs 64, UP vs SMP, PAE vs non-PAE...). An explicit design intent of all the Xen work is that it can be compile-time enabled without any (significant) effect on native performance, so that the decision to enable Xen doesn't have any downsides (either in terms of raw performance or maintenance of the kernel package).

if so, instead of using IFDEF`s, can`t the critical path`s being generously circumvented by default, (if, else...), needing some dom0 kernel bootparam to be activated (i.e. use
the kernel as dom0 kernel) ?
Well, broadly speaking, yes. We try to avoid putting if/thens in critical paths, and where there are changes to hot patches, we use dynamic code patching to make it as efficient as possible.

J
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