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Re: x86 release builds are slow

On May 3, 2008, at 20:30 , Manuel Bouyer wrote:

On Sat, May 03, 2008 at 07:13:26PM +0100, Andrew Doran wrote:
DOMU kernels don't need any physical device drivers (and because of this,
DOMU kernels build much faster than dom0 kernels). There's an issue
with XPMAP_OFFSET being different in some cases.
It should be possible to have a kernel that can work both dom0 and domU
for Xen >= 3.1

I will try a few experiments but it will be a while before I have the time. I'm also interested in the possibility of using multiboot to pass a root
disk image or module to the DOMU kernels for installs.

I'm not sure how Xen actually deal with that for domUs. I don't think it's
multiboot (but it may be close to multiboot).

but that would make a heavily-bloated domU kernel.
I'd prefer to keep separate domU kernels, with only the needed code for
domU operations (A Xen3 dom0 kernel is 9.5MiB, a domU kernel is less
than 4MiB).

I think that's simply fallacious. Yes, our kernels are too fat and we are working on that, but you would be hard pushed today to buy a new PC off the shelf with less than 512MB of RAM. We're speaking of virtualization, not embedded systems or constrained systems that can just about support one OS.

please stop assuming we can always throw more hardware to fix software bloat.
It's just not true.

I haven't used Xen intensively, but one would expect to have multiple (= many) domU's in a single machine, right? Then, the overhead for each kernel can be noticeable, can't it?

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