Re: xen-unstable: build fails

[Juergen Gross <juergen.gross@ts.fujitsu.com>]

On 03/16/11 17:50, Keir Fraser wrote:
> On 16/03/2011 13:50, "Juergen Gross"<juergen.gross@ts.fujitsu.com>  wrote:
>
>> Hi,
>>
>> I've just set up a machine with OpenSuse 11.4 and tried to build Xen.
>>
>> Under root I did:
>>
>> hg clone http://xenbits.xensource.com/xen-unstable.hg
>> cd xen-unstable.hg
>> make xen
>>
>> The make failed with:
>>
>> make[4]: Entering directory `/root/xen-unstable.hg/xen/arch/x86/boot'
>> RELOC=0x7c000 make -f build32.mk reloc.S
>> make[5]: Entering directory `/root/xen-unstable.hg/xen/arch/x86/boot'
>> make[5]: *** ../../../../.config: Is a directory.  Stop.
>
> Seems to me that /root/xen-unstable.hg/xen/arch/x86/boot/../../../../.config
> resolves to /root/xen-unstable.hg/.config. Which is what is intended. Also I
> tried creating a .config dir just outside my own xen-unstable repo, and
> rebuoilding the hypervisor, and it works okay for me.

Okay, I checked it.
My build environment is under /root/xen-unstable.hg
I have .config directories in / and in /root
I created .config files on another machine without those directories in / and
in /root with a make error statement indicating which file is used:

make[4]: Entering directory `/root/xen-unstable.hg/xen/arch/x86/boot'
RELOC=0x7c000 make -f build32.mk reloc.S
make[5]: Entering directory `/root/xen-unstable.hg/xen/arch/x86/boot'
../../../../.config:1: *** error form /.config.  Stop.
make[5]: Leaving directory `/root/xen-unstable.hg/xen/arch/x86/boot'
make[4]: *** [reloc.S] Error 2
make[4]: Leaving directory `/root/xen-unstable.hg/xen/arch/x86/boot'
make[3]: *** [/root/xen-unstable.hg/xen/arch/x86/boot/built_in.o] Error 2
make[3]: Leaving directory `/root/xen-unstable.hg/xen/arch/x86'
make[2]: *** [/root/xen-unstable.hg/xen/xen] Error 2
make[2]: Leaving directory `/root/xen-unstable.hg/xen'
make[1]: *** [install] Error 2
make[1]: Leaving directory `/root/xen-unstable.hg/xen'
make: *** [install-xen] Error 2


The reason is clear: XEN_ROOT is set to a *relative* path. And when make is
including a Makefile, it switches the working directory to the directory of
the included Makefile. Including another Makefile via XEN_ROOT then is the
problem...

>
>> The reason seems to be a directory /root/.config which isn't present on my
>> other machines.
>
> We shouldn't be referring outside the repository. AFAICS the above logging
> doesn't indicate that we are. I don't understand why you are getting that
> error. I haven't been able to reproduce it.

I have :-(

>
>> fails in a similar way. Many Makefiles seem to contain lines like:
>>
>> XEN_ROOT=../..
>>
>> which is a really bad idea in my opinion. XEN_ROOT should only be set, if it
>> is not yet defined.
>
> Why? It's private to our build system. We don't want the user screwing with
> it. I also don't see why relative paths within our repository should be
> avoided, as you try to do in your alternative formulation.

You have to avoid relative paths in make variables used in different directory
levels.


Juergen

-- 
Juergen Gross                 Principal Developer Operating Systems
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