Re: [BUG] XEN 4.3.3 - segfault in xl create for HVM with PCI passthrough

[Atom2 <ariel.atom2@web2web.at>]

Ian,
Thanks again for your reply.

Am 10.11.14 um 12:16 schrieb Ian Campbell:
> On Thu, 2014-11-06 at 16:11 +0100, Atom2 wrote:
>
> Is it at all possible to recompile at least the Xen toolstack bits with
> these extra gcc features disabled? Either by using the old compiler or
> somehow (CFLAGS?) disabling those features of the new one.
The old compiler (after I brought it in again) for reasons unknow to me 
still seemed to use the version of libgcc_s.so.1 from the newer compiler 
(which was part of the segfault issue - see my latest post from Sunday 
with debugging enabled for gcc and glibc and a full backtrace). But 
downgrading a compiler is anyways something that everybody warns from, 
so I then reverted back to gcc-4.8.3

Re disabling the hardened features for the compiler: I have also tested 
that over the weekend for xen-* stuff with the 4.8.3 compiler (I 
selected the vanilla variant of gcc for the compile process of the 
xen-bits) and that did not change anything - it was still segfaulting. 
But it's worth pointing out that test the rest of the system (including 
kernel, glibc and the rest of world) was still using the hardened toolchain.
>
> I'm afraid it's looking more and more like a toolchain issue. I'm not
> expert on this side on things but it looks to me like you are hitting an
> issue with some sort of buffer overflow check gone wrong? I think you'll
> need a gcc hardening person for this one.
The issue currently is with the guys at gentoo (for links please again 
see my latest post to the list from Sunday which also seems to confirm 
that the issue is not confined to 4.3.3 but also 4.4.1).

Thanks Atom2