Re: [RFC 7/7] libxl: Wait for QEMU startup in stubdomain

[Anthony PERARD <anthony.perard@citrix.com>]

On Mon, Feb 09, 2015 at 09:07:13AM +0000, Ian Campbell wrote:
> On Fri, 2015-02-06 at 17:23 +0000, Stefano Stabellini wrote:
> > > 
> > > One of the main issues outstanding from when Anthony originally posted
> > > his patches is how we want to go about building this?  I honestly do
> > > not know how well the current dracut-based approach to building the
> > > root image will work across various Linux distributions; perhaps it
> > > will be OK, since all of the libraries that dracut will siphon in will
> > > have to be in place to meet the build requirements for QEMU to begin
> > > with. 
> > >
> > > However, I have zero knowledge about ARM-based Xen or where
> > > NetBSD is used for dom0, and how they might affect the decisionmaking.
> > > I also do not know what lessons have been learned from building other
> > > stubdoms, rumpkernel, or Mirage that might inform these decisions.
> > > In other words, what do you see as a sensible build scheme?  The
> > > approach taken in the patches strikes me as too hacky for release
> > > quality, but maybe it is OK...
> >  
> > It looks OK to me but I am not an expert in this kind of things. I'll
> > let Ian Campbell and Ian Jackson (CC'ed) comment on it.
> 
> I'm not at all keen on things like the use of dracut (or mkinitramfs or
> similar) in Xen's build since they are inherently/inevitably specific to
> the Linux distro they came from, so they often don't work (or aren't
> even available on) other Linux distros and are an even bigger problem
> for *BSD.

I'd like to precise that the use of dracut here is only to copy a binary
and it's dependencies (shared libraries), the binary used is called
dracut-installer. I guest that the same can be achieved by the copy_exec()
function from mkinitramfs (found in
/usr/share/initramfs-tools/hook-functions on a debian system).

The rest is done by a script, which choose which binary and file to include
in the rootfs, where to put them and how to generate the image.

-- 
Anthony PERARD