Re: [Xen-devel] Stubdom GMP build failure for gcc 6

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Fri, Oct 28, 2016 at 04:44:10PM +0200, Juergen Gross wrote:
> On 28/10/16 14:10, Wei Liu wrote:
> > Hi all
> > 
> > There have been a few reports on stubdom build failure with gcc 6
> > toolchain. I spent some time yesterday to figure what went wrong. Here
> > is what I found.
> > 
> > When building GMP library, its configure script generates small C
> > programs to determine various aspects of the system. Unfortunately the
> > build rune for it is incorrect, so the test program ends up consuming
> > newlib headers while linking against the host glibc. It's amazing that
> > this even worked in the past few years! :-)
> > 
> > Unfortunately my attempt to fix it by providing LDFLAGS="-nostdlib
> > -LXXX" doesn't work. It turns out that there is no crt generated in
> > newlib. I'm not sure if that's because the newlib port is incomplete or
> > I haven't discovered a way to teach it to generate one.
> > 
> > So what should we do with this? I'm not sure if I can come up with a
> > non-intrusive patch quickly.  GMP is only used by tpm emulator, so for
> > the imminent 4.8 release I can write a patch to disable building that.
> > 
> > Ultimately we need to have a proper solution, because there can be other
> > breakages in the future. And I do wish users who need tpm emulator can
> > continue to use it. I don't have a clear answer as to how many people
> > care about this and how can we fix it.
> > 
> > Thoughts?
> 
> I just tried to verify it is working (or failing) for me. On the machine
> I normally did my Xen builds cmake was missing so it never tried to
> build libgmp. After installing it I saw the following problem:
> 
> at the end of libgmp build:
> Libraries have been installed in:
>    /home/gross/xen/stubdom/cross-root-x86_64/x86_64-xen-elf/lib64
> 
> and when trying to link stubdom-vtpm:
> make[2]: Entering directory '/home/gross/xen/extras/mini-os-remote'
> ld -r -d -nostdlib
> -L/home/gross/xen/stubdom/cross-root-x86_64/x86_64-xen-elf/lib  -m
> elf_x86_64 -\( /home/gross/xen/stubdom/vtpm/vtpm.a -T app.lds -\) -ltpm
> -ltpm_crypto -lgmp -lpolarssl --undefined main -o
> /home/gross/xen/stubdom/mini-os-x86_64-vtpm/mini-os_app.o
> ld: cannot find -lgmp
> 
> manually adding
> "-L/home/gross/xen/stubdom/cross-root-x86_64/x86_64-xen-elf/lib64" lets
> the link command succeed.
> 

This is a different issue from the one I report here.

But both stems from the fact that we don't really create a complete
cross-compile toolchain for stubdom, but piggy-back on the host
toolchain.

Presumably you didn't see my issue because you're using an older version
of glibc.

Wei.

> 
> Juergen

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