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Re: x86 release builds are slow

On Thu, May 01, 2008 at 02:06:31AM +0100, Andrew Doran wrote:
> Hi,
> For an i386 release build we now build 11 kernels, which takes a long time.
> To help verification of changes it would be better if release builds didn't
> take so long.
> For i386 and amd64, we could change the process so that the GENERIC kernel
> is used for installs, and the root file system objcopy'd into a seperate ELF
> binary that is loaded by the boot loader. We could modify the in-kernel ELF
> linker to set the root file system image up. Any comments on that?
> For xen that might not be possible because GRUB is used. I don't know. If it
> can't be done, what are the major reasons for having seperate DOM0 and DOMU
> kernels?

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, 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).

Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference

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