Re: [Xen-users] how to boot something to get a vm started

[hw <hw@xxxxxxxxxxxxxxxxxxxxxxxx>]

Am 13.07.2015 um 18:22 schrieb Ian Campbell:
> On Mon, 2015-07-13 at 18:01 +0200, hw wrote:
> > xc: error: Could not open kernel image (2 = No such file or directory):  
> > Internal error
> Strange. This suggests that hvmloader isn't available for some reason.
> What version of Xen is this? On what distro
It's an up-to-date Gentoo, not sure how to find out what xen version it has.

> Do you have $prefix/lib/xen/boot/hvmloader ? If not then is it at some
> other path?
'find / -name hvmloader' doesn't find any files, so I take it it's not 
available.
Am I supopsed to expect that the VM is booting from the ISO when I 
create it (which is what I do), or am I missing something else?
Hmmm ... The 'xen-tools' package has USE flags, according to 
http://gentoobrowse.randomdan.homeip.net/package/app-emulation/xen-tools 
--- among them 'hvm'.  I do not have this USE flag at all:

moonflo ~ # equery uses xen-tools
[ Legend : U - final flag setting for installation]
[        : I - package is installed with flag     ]
[ Colors : set, unset                             ]
 * Found these USE flags for app-emulation/xen-tools-4.5.1-r1:
 U I
 - - api                      : Build the C libxenapi bindings
 - - custom-cflags            : Build with user-specified CFLAGS 
(unsupported)
 - - debug                    : Enable extra debug codepaths, like 
asserts and extra output. If you want to get meaningful backtraces see
https://wiki.gentoo.org/wiki/Project:Quality_Assurance/Backtraces
 - - doc                      : Add extra documentation (API, Javadoc, 
etc). It is recommended to enable per package instead of globally
 - - flask                    : Enable the Flask XSM module from NSA
 - - ovmf                     : Enable support to boot UEFI guest vm, 
needed by hvm
 + + pam                      : Enable pam support
 - - pygrub                   : Install the pygrub boot loader
 - - python                   : Add optional support/bindings for the 
Python language
 + + python_targets_python2_7 : Build with Python 2.7
 - - qemu                     : Enable IOEMU support via the use of qemu-dm
 - - screen                   : Enable support for running domain U 
console in an app-misc/screen session
 - - static-libs              : Build static versions of dynamic 
libraries as well
 - - system-qemu              : Using app-emulation/qemu instead of the 
bundled one
 - - system-seabios           : Using sys-firmware/seabios instead of 
the bundled one
moonflo ~ #


I'll ask about this on the Gentoo mailing list.

> [...]
> > '/isolinux/gentoo' is listed in the grub.cfg contained in the ISO, and
> > it does exist.
> Booting a PV guest from an ISO is a bit subtle,
> http://wiki.xen.org/wiki/Debian_Guest_Installation_Using_Debian_Installer#Create_Initial_Guest_Configuration_2
>  shows how it can be done for Debian, I reckon something similar ought to be 
> possible for gentoo.
Thanks, maybe that can somehow be applied to the Gentoo ISO.  It might 
be easier to create a hvm guest booting from the Gentoo ISO --- if it 
was possible to boot something at all ...
I could also boot the whole server from an USB stick to do the 
installation, but at least for the windoze guest, I have doubts that it 
would run when virtualized.
Why do they make it so impossible to install guests on xen to begin with?

> Without using pygrub as described there the toolstack will be looking
> for /isolinux/gentoo on your dom0 filesystem.
Well, pygrub isn't installed.  I could install it, but I was planning to 
install a Gentoo VM only later once the windoze VM is finally running. 
Maybe it doesn't work at all, and the time would be wasted.
What sense would it make to look for files which belong to the guest 
which is to be installed within the file system of the host?  When 
specifying such files, of course I expect them to be looked for within 
the guest.  The host has already booted and is running.
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