Red Hat Bugzilla – Bug 214148
"4gb seg fixup, process beagle-build-in" message on FC6 with Xen
Last modified: 2007-11-30 17:11:47 EST
Description of problem:
On a stock FC6 with virtualization support installed (kernel, Xen, etc.), the
following message appears continuously after installation, "dirting" the screen:
4gb seg fixup, process beagle-build-in (pid 10967), cs:ip 73:0811cbff
(the last number, after, ":", is always variable)
The computer performs otherwise normally, except that the console is always
occupied by this continuous stream of messages, making almost impossible to
enter any command.
The message appears 30-40 times/minute.
The machine is a 1,6 MHz Pentium 4, 512 MB RAM, Intel motherboard.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
The above message appears continuously.
The message shouldn't appear at all.
This message is highlighting bad behaviour by the beagle binary which is always
going to result in slow performance under Xen.
glibc on i386 uses a special segment register as a base for thread-local
storage. But by default it accesses data both on from positive and negative
offsets of that register; that behaviour causes a kernel trap under Xen each
time it switches from positive to negative, as there is simply no way on x86
architecture to set up a segment register covering just user space that allows
both positive and negative offsets, and Xen requires that the register not cover
glibc has been updated to detect this case and avoid negative segment offsets
for Xen. I don't know why beagle should be causing the same problem; is it
compiled with some old static library that does not know about nosegneg libraries?
I've checked that I have a recent glibc, and it is configured with nosegneg.
This is a FC5 xenU rather than a FC6, but I suspect there are similar issues.
There is a huge number of processes that are showing these problems, more than
I think can be because of being statically linked.
Here are a few examples:
Nov 8 03:10:01 calcutta kernel: 4gb seg fixup, process ifup-eth (pid 678),
Nov 8 03:10:03 calcutta kernel: 4gb seg fixup, process xinetd (pid 906), cs:ip
Nov 8 03:10:08 calcutta kernel: 4gb seg fixup, process crond (pid 1071), cs:ip
Nov 8 03:10:13 calcutta kernel: 4gb seg fixup, process httpd (pid 1098), cs:ip
Nov 8 03:10:18 calcutta kernel: 4gb seg fixup, process httpd (pid 1099), cs:ip
Nov 8 03:10:24 calcutta kernel: 4gb seg fixup, process sendmail (pid 1043),
Nov 8 03:10:28 calcutta kernel: 4gb seg fixup, process tcsh (pid 1114), cs:ip
Nov 8 03:10:33 calcutta kernel: 4gb seg fixup, process sendmail (pid 1043),
Nov 8 03:10:38 calcutta kernel: 4gb seg fixup, process tcsh (pid 1114), cs:ip
A dup of bug 210001.
We did enable the "xen" mode in our mono which changes the way TLS is handled to
be xen-friendly (as seen in the bug). But it doesn't seem to help.
*** This bug has been marked as a duplicate of 210001 ***