On Mon, Jul 02, 2012 at 10:04:13AM -0500, W. Michael Petullo wrote: > >> I am attempting to run Xen on an AMD FX-4170 Quad-Core Processor. > >> I have installed Fedora 17 to serve as Dom0. > >> > >> I am finding that Python does not run well on this > >> configuration. Specifically, "import random" causes the Python interpreter > >> to terminate with "Illegal instruction". This means that xend and yum will > >> not run. > >> > >> I filed a bug under yum [1], but just realized that things work if I > >> boot Fedora 17 on bare metal. > >> > >> Under Xen, /proc/cpuinfo reports the following flags: > >> > >> fpu de tsc msr pae cx8 apic cmov pat clflush mmx fxsr sse sse2 ht syscall > >> nx mmxext fxsr_opt lm constant_tsc rep_good nopl nonstop_tsc extd_apicid > >> aperfmperf pni pclmulqdq ssse3 cx16 sse4_1 sse4_2 popcnt aes hypervisor > >> lahf_lm cmp_legacy extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch > >> xop fma4 perfctr_core arat cpb hw_pstate > >> > >> Has anyone had similar trouble? > > > No. But it sounds like the AVX disaster. > > > > https://bugzilla.redhat.com/show_bug.cgi?id=801650 > > It seems to be. > > I booted bare metal and used yum to install gdb and the debug symbols > for Python and glibc. > > Then I rebooted in Xen. I found that gdb itself crashed when the debug > symbols were installed, so I removed them. I ran gdb again and obtained > a partial backtrace on "import random": > > (gdb) ba > #0 0x00007ffff71474ec in __ieee754_exp_fma4 () from /lib64/libm.so.6 > #1 0x00007ffff009e415 in ?? () from /usr/lib64/python2.7/lib-dynload/math.so > #2 0x00007ffff7b00053 in PyEval_EvalFrameEx () from /lib64/libpython2.7.so.1.0 > #3 0x00007ffff7b00b2f in PyEval_EvalCodeEx () from /lib64/libpython2.7.so.1.0 > #4 0x00007ffff7b00c02 in PyEval_EvalCode () from /lib64/libpython2.7.so.1.0 > #5 0x00007ffff7b1017d in PyImport_ExecCodeModuleEx () from /lib64/libpython2.7.so.1.0 > [...] > > After looking a little closer, it seems that __ieee754_exp_fma4 is > executing "vmovsd %xmm0,-0x20(%rsp)". > > I thought booting Xen with xsave=1 might help, but this causes Xen to > crash on this hardware. As mentioned above, it looks like there has been Right. That is b/c of Fedora's incorrect extra patch that neuters xsave. > work in glibc to properly detect AVX (my understanding is that you have > to check that both the processor and OS supports it). Is it possible > that this glibc work missed something? Very likely. There was another fix to it that got added in Debian (or Ubuntu) that checked for FMA4 on AMD (which had a different CPUID). Can you open a Red Hat bugzilla please? And CC me on it: ketuzsezr@xxxxxxxxxx > > -- > Mike > > :wq -- xen mailing list xen@xxxxxxxxxxxxxxxxxxxxxxx https://admin.fedoraproject.org/mailman/listinfo/xen
