Re: can't start hvm with network

[Elliott Mitchell <ehem+xen@xxxxxxx>]

On Mon, Mar 17, 2025 at 04:57:03PM +0100, Paul Leiber wrote:
> Hi Kevin,
> 
> Am 17.03.2025 um 16:01 schrieb Kevin Wang:
> 
> On another note: Why are you using HVM for setting up a linux DomU? I never
> tested Ubuntu myself, but for Debian (and most likely Debian-based)
> distributions, PV should the better option. Again, [2] shows how to install
> a Debian PV DomU, and the procedure is still working (of course, wheezy is a
> bit outdated and needs to be replaced, e. g. with bookworm). The section
> even mentions Ubuntu distributions, so it's probably worth to dig deeper
> there.

If you have even fairly old hardware, rather superior to PV mode is PVH
mode.  After a few generations of AMD64 hardware all the processors
started adding an extra page table level.  PVH mode lets the kernel use
PV drivers, but then use normal page tables on top.  Needs a bit of
adjustment from PV mode, but yields rather better performance.

I've found HVM mode somewhat handier for initial installation, but once
installed PVH mode is better (except for the issue of booting non-Linux).


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