Re: [Xen-users] Cross-compiling tool stack for ARM

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2014-05-28 at 12:14 +0100, Jeenu Viswambharan wrote:
> On Wed, May 28, 2014 at 11:00:59, Ian Campbell wrote:
> > On Tue, 2014-05-27 at 15:56 +0100, Jeenu Viswambharan wrote:
> > > Hi,
> > >
> > > I'm new to Xen but am comfortable with ARM virtualization. I'm
> > > trying to build a system running Xen on Vexpress TC2 board, with a
> > > single guest.
> > >
> > > From what I've learned so far, I should build u-boot, Xen, Dom0
> > > guest, Xen tool stack, and a DomU guest to get there. I've followed
> > > Wiki pages [1][2] to built u-boot and Xen.
> >
> > I take it you haven't seen
> > http://wiki.xenproject.org/wiki/Xen_ARM_with_Virtualization_Extensions/CrossCompiling
> > which goes into some detail about cross compiling the tools?
> 
> Yes, I did see them. But does it mean that it's a mandatory step?

What is? That is a set of instructions for how to setup and cross
compile environment and use it. Is there a step there which you want to
know is optional?

>  It's
> quite tempting for a user to just download and use a binary distributor
> for cross compilation tool chain.

A toolchain != a build environment. A toolchain is a compiler and,
maybe, a libc. That might be fine for building a kernel but it's
obviously not sufficient for building any userspace tool which has other
build dependencies.


> 
> > > The tool chain that I'm using is from Linaro, and I verified that it
> > > doesn't come with any '.pc' files. Could you suggest a way to
> > > proceed with the compilation?
> >
> > As well as a toolchain you will also need a cross compile environment
> > with all of the appropriate library's development headers, which should
> > include the .pc files. The link above covers setting up a suitable
> > Ubuntu cross environment.
> 
> I managed to get by the build problems posted earlier by installing ARM
> tool chain using APT, but later hit the wall because libaio isn't
> available.

Well, it was available in ubuntu when I wrote
http://wiki.xen.org/wiki/Xen_ARM_with_Virtualization_Extensions/CrossCompiling

If you are following those instructions and something isn't working then
please report specifics so we can fix them.

>  So things look more like I'd have to build the tool chain
> myself. If the whole build expects a freshly built tool chain, I think
> the Wiki must explicitly state that.

It doesn't expect anything of the sort.

Please, just follow the existing instructions given and if you have
problems with that then ask. Going off on random tangents is just
leading to you reaching incorrect conclusions and making more work for
yourself.

> The Wiki page reads the target chroot must match the runtime system. So
> I take it that I've to use the Saucy Salamander as my dom0

Yes.

> (i.e. build it from sources),

No. why would you conclude that? Ubuntu is a binary distribution.

> with a root file system created following instructions
> from another page.
> 
> Silly question: what if I want to build a bare minimum system (maybe
> headless)?

That is what the current instructions do.

>  Can I have a dom0 guest built from mainline Linux master,
> with a root file system built as described in the Wiki?

There is approximately zero linkage between your kernel and your
userspace other than a requirement for certain drivers to be installed.

> Meanwhile, I'll try to follow the wiki to build my tool chain and root
> file system.

Yes, that would be best I think.

Ian.


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