Red Hat Bugzilla – Bug 153775
[RHEL3-U6][Diskdump] Backtrace of OS_INIT doesn't work
Last modified: 2010-10-21 22:52:13 EDT
Description of problem:
When crashdump is executed via OS_INIT on IPF machine, backtrace command,
which is a subcommand of crash, does not work correctly.
Two problems were found in the OS_INIT code.
(1) OS_INIT handler has two stages.
stage1: handler written by assembler
stage2: handler written by C
The former is ia64_monarch_init_handler and ia64_slave_init_handler.
The latter is ia64_init_handler. ia64_init_handler is called only by
When INIT interrupt is asserted, one cpu calls
ia64_monarch_init_handler and the others call
ia64_slave_init_handler. It means that ia64_init_handler is called
by only one cpu. In that case, backtrace command fails. To make
backtrace succeed, all cpus need to call ia64_monarch_init_handler.
(2) The second problem occurs by correcting the first problem.
When OS_INIT handler is called, SAL hands handler some information
through register. The handler preserves this information in
ia64_sal_to_os_handoff_state. (Please see
SAL_TO_OS_MCA_HANDOFF_STATE_SAVE macro in the arch/ia64/kernel/
mca_asm.S.) If all cpus call ia64_monarch_init_handler at the same
time, they writes their own information to the
ia64_sal_to_os_handoff_state simultaneously and break its contents.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Enable Diskdump
2. Push OS_INIT switch
3. bt with crash command
Backtrace command does not work
Backtrace command works correctly
How to correct these problems:
(1) When OS_INIT handler is registered with SAL,
register ia64_monarch_init_handler as both monarch handler and slave
(2) Prepare ia64_sal_to_os_handoff_state of each cpu beforehand.
Created attachment 112728 [details]
The patch is provided by Fujitsu on IT#69948.
The fix for the issue will be targeted for RHEL3-U6.
A fix for this problem has just been committed to the RHEL3 U6
patch pool this evening (in kernel version 2.4.21-32.5.EL).
To verify the fix, we've done testing with kernel-2.4.21-32.9.EL. It works
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.