[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] Re: "hwcap 0 nosegneg" doesnt work with paravirt_ops xen as of 2.6.23.9
Andres Freund wrote: > after converting a host from using a ubuntu patched 2.6.22 domU to using > 2.6.23 xen via paravirt_ops (no configuration change except devicename change > in fstab, and another getty running) ldconfig no longer picks up the nosegneg > libc leading to segfaults for some programs. > It shouldn't ever lead to segfaults. At worst, you should get poor performance because the hypervisor emulates the -ve segment offset. > /etc/ld.so.conf.d/xen.conf: > hwcap 0 nosegneg > This looks OK. If this doesn't work, then it suggests there's something wrong with the kernel vdso which is not exporting the nonegseg (pseudo-)hardware capability. But we've gone over this several times now, and I was fairly sure we'd finally got it right - works for me, at least. The alternative is that there's some bug on the userspace side in your version of Ubuntu... Roland? > On ubuntu's 2.6.22-xen: > ldd /usr/bin/perl > linux-gate.so.1 => (0xf57fe000) > libdl.so.2 => /lib/tls/i686/nosegneg/libdl.so.2 (0xb7f90000) > libm.so.6 => /lib/tls/i686/nosegneg/libm.so.6 (0xb7f6b000) > libpthread.so.0 => /lib/tls/i686/nosegneg/libpthread.so.0 (0xb7f53000) > libc.so.6 => /lib/tls/i686/nosegneg/libc.so.6 (0xb7e05000) > libcrypt.so.1 => /lib/tls/i686/nosegneg/libcrypt.so.1 (0xb7dd7000) > /lib/ld-linux.so.2 (0xb7f9d000) > > On selfcompiled 2.6.23.9: > ldd /usr/bin/perl > linux-gate.so.1 => (0xf57fc000) > libdl.so.2 => /lib/tls/i686/cmov/libdl.so.2 (0xb7f3b000) > libm.so.6 => /lib/tls/i686/cmov/libm.so.6 (0xb7f16000) > libpthread.so.0 => /lib/tls/i686/cmov/libpthread.so.0 (0xb7efe000) > libc.so.6 => /lib/tls/i686/cmov/libc.so.6 (0xb7db3000) > libcrypt.so.1 => /lib/tls/i686/cmov/libcrypt.so.1 (0xb7d85000) > /lib/ld-linux.so.2 (0xb7f46000) > > > I now discover, that after some playing around (during discovering what the > problem is) i must have changed something, because ldd still shows the use of > the i686/cmov libraries, but applications reliably causing crashes earlier, > dont do so anymore. > As I said, you shouldn't be seeing crashes either way. If you are, it suggests a hypervisor bug. Does "xm dmesg" show anything? > Perhaps Im all wrong, and paravirt_ops doesnt need the nosegneg versions and > just a ldconfig or so (which seems strange because the result before and > after the ldconfig were the same). > nosegneg is still necessary, and it should still be working as it did before. > PS: I did this conversion mainly, because I was getting quite random crashes > inside the domU. I guess, as this was a vendor kernel + xensource xen kernel, > this isnt appropriate for lkml? As well as the crashes of the Dom0 (ubuntu > again)? > Yeah, anything which isn't 2.6.18-xen isn't officially "Xen project", but its worth reporting the bugs to xen-devel (and Ubuntu, of course). And to me, for that matter. I won't be able to help directly, but the crashes may highlight things we need to be careful about in the pvops Xen support. J _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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