Re: [gentoo-user] installing Gentoo as a xen guest

[J. Roeleveld]

On Thursday, September 24, 2015 03:33:28 PM Håkon Alstadheim wrote:
> Den 24. sep. 2015 14:53, skrev Rich Freeman:
> > On Thu, Sep 24, 2015 at 6:05 AM, hw <hw@×××××.de> wrote:
> >> Hi,
> >>
> >> I'm installing Gentoo as a xen PV guest.  Do I need to install a
> >> bootloader
> >> like grub, or should I rather just specify the kernel to boot in the
> >> definition file of the guest?  If I do the latter, what about the kernel
> >> command line?
> >>
> >> Is there anything I should consider?  The host is also running Gentoo.
> >
> > You can do either.  I suspect it would be easier to just use grub.  I
> > don't know if xen provides a way to provide a command-line, if not you
> > could build a default command-line into your kernel.
>
> Depending on your hardware you will want to use hvm or pvm for
> efficiency. (VT-x means hvm is more efficient).

What do you base this on?
Without VT-x, HVM doesn't even work, which means PV is only option.

With VT-x, PV still has higher performance as the drivers inside the guest 
talk directly to the host.

> If running hvm on
> quemu-xen-traditional, you HAVE to use a bootloader inside the VM, or
> some kind of netboot/pvgrub thing. If running upstream quemu for a hvm,
> you can choose. I find it less of a hassle to use bootloader inside the
> VM.

It's simple, if you don't have full access to the host.
If you have full access, it's actually simpler as you don't have to worry 
about boot-order, partitioning and a bootloader.

> If running pv, I BELIEVE you have to specify kernel and boot options
> outside the VM-image, possibly through pvgrub. Pvgrub is supposed to be
> able to fish out kernel and initrd from the VM disk. I never bothered to
> get that working. Here is an example excerpt from a PVM I use (for a
> debian vm):
> --print.pvm---
> builder = "generic"
> kernel = "/etc/xen/wheezy/vmlinuz-3.16.0-0.bpo.4-amd64"
> ramdisk = "/etc/xen/wheezy/initrd.img-3.16.0-0.bpo.4-amd64"
> extra = "root=/dev/xvda console=hvc0 tmem"
> --
> For explanation check "man xl.cfg". When you specify
> kernel&ramdisk&parameters in the vm config, you do NOT need a /boot/
> directory on your vm.  Obviously when you build a kernel inside the vm,
> it will end up in /boot, so you have to provide a way for the
> dom0/hypervisor to load your kernel, either (when using full
> virtualization) a regular boot-loader inside the vm, or (for a PV guest)
> through some other means to let the dom0/hypervisor load your image.

--
Joost