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xen-devel
[Xen-users] Re: Xen is a feature
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To: |
Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> |
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Subject: |
[Xen-users] Re: Xen is a feature |
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From: |
Avi Kivity <avi@xxxxxxxxxx> |
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Date: |
Tue, 02 Jun 2009 21:59:19 +0300 |
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"jens.axboe@xxxxxxxxxx" <jens.axboe@xxxxxxxxxx>, ksrinivasan <ksrinivasan@xxxxxxxxxx>, Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, "wimcoekaerts@xxxxxxxxxxxx" <wimcoekaerts@xxxxxxxxxxxx>, "gregkh@xxxxxxx" <gregkh@xxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxxxxx>, "linux-kernel@xxxxxxxxxxxxxxx" <linux-kernel@xxxxxxxxxxxxxxx>, "x86@xxxxxxxxxx" <x86@xxxxxxxxxx>, "jeremy@xxxxxxxx" <jeremy@xxxxxxxx>, David Miller <davem@xxxxxxxxxxxxx>, "npiggin@xxxxxxx" <npiggin@xxxxxxx>, Ian Pratt <Ian.Pratt@xxxxxxxxxxxxx>, Stephen Spector <stephen.spector@xxxxxxxxxx>, Keir Fraser <Keir.Fraser@xxxxxxxxxxxxx>, "EAnderson@xxxxxxxxxx" <EAnderson@xxxxxxxxxx>, "kurt.hackel@xxxxxxxxxx" <kurt.hackel@xxxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, "xen-users@xxxxxxxxxxxxxxxxxxx" <xen-users@xxxxxxxxxxxxxxxxxxx>, "mingo@xxxxxxx" <mingo@xxxxxxx> |
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Linus Torvalds wrote:
The point? Xen really is horribly badly separated out. It gets way more
incestuous with other systems than it should. It's entirely possible that
this is very fundamental to both paravirtualization and to hypervisor
behavior, but it doesn't matter - it just measn that I can well see that
Xen is a f*cking pain to merge.
So please, Xen people, look at your track record, and look at the issues
from the standpoint of somebody merging your code, rather than just from
the standpoint of somebody who whines "I want my code to be merged".
IOW, if you have trouble getting your code merged, ask yourself what _you_
are doing wrong.
There is in fact a way to get dom0 support with nearly no changes to
Linux, but it involves massive changes to Xen itself and requires
hardware support: run dom0 as a fully virtualized guest, and assign it
all the resources dom0 can access. It's probably a massive effort though.
I've considered it for kvm when faced with the "I want a thin
hypervisor" question: compile the hypervisor kernel with PCI support but
nothing else (no CONFIG_BLOCK or CONFIG_NET, no device drivers), load
userspace from initramfs, and assign host devices to one or more
privileged guests. You could probably run the host with a heavily
stripped configuration, and enjoy the slimness while every interrupt
invokes the scheduler, a context switch, and maybe an IPI for good measure.
--
Do not meddle in the internals of kernels, for they are subtle and quick to
panic.
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