patch-2.0.18 linux/Documentation/oops-tracing.txt

• Lines: 82
• Date: Wed Sep 4 20:37:21 1996
• Orig file: v2.0.17/linux/Documentation/oops-tracing.txt
• Orig date: Sat May 11 10:08:34 1996

diff -u --recursive --new-file v2.0.17/linux/Documentation/oops-tracing.txt linux/Documentation/oops-tracing.txt
@@ -70,3 +70,81 @@
 
 		Linus
 
+
+---------------------------------------------------------------------------
+Notes on Oops tracing with klogd:
+
+In order to help Linus and the other kernel developers there has been
+substantial support incorporated into klogd for processing protection
+faults.  In order to have full support for address resolution at least
+version 1.3-pl3 of the sysklogd package should be used.
+
+When a protection fault occurs the klogd daemon automatically
+translates important addresses in the kernel log messages to their
+symbolic equivalents.  This translated kernel message is then
+forwarded through whatever reporting mechanism klogd is using.  The
+protection fault message can be simply cut out of the message files
+and forwarded to the kernel developers.
+
+Two types of address resolution are performed by klogd.  The first is
+static translation and the second is dynamic translation.  Static
+translation uses the System.map file in much the same manner that
+ksymoops does.  In order to do static translation the klogd daemon
+must be able to find a system map file at daemon initialization time.
+See the klogd man page for information on how klogd searches for map
+files.
+
+Dynamic address translation is important when kernel loadable modules
+are being used.  Since memory for kernel modules is allocated from the
+kernel's dynamic memory pools there are no fixed locations for either
+the start of the module or for functions and symbols in the module.
+
+The kernel supports system calls which allow a program to determine
+which modules are loaded and their location in memory.  Using these
+system calls the klogd daemon builds a symbol table which can be used
+to debug a protection fault which occurs in a loadable kernel module.
+
+At the very minimum klogd will provide the name of the module which
+generated the protection fault.  There may be additional symbolic
+information available if the developer of the loadable module chose to
+export symbol information from the module.
+
+Since the kernel module environment can be dynamic there must be a
+mechanism for notifying the klogd daemon when a change in module
+environment occurs.  There are command line options available which
+allow klogd to signal the currently executing daemon that symbol
+information should be refreshed.  See the klogd manual page for more
+information.
+
+A patch is included with the sysklogd distribution which modifies the
+modules-2.0.0 package to automatically signal klogd whenever a module
+is loaded or unloaded.  Applying this patch provides essentially
+seamless support for debugging protection faults which occur with
+kernel loadable modules.
+
+The following is an example of a protection fault in a loadable module
+processed by klogd:
+---------------------------------------------------------------------------
+Aug 29 09:51:01 blizard kernel: Unable to handle kernel paging request at virtual address f15e97cc
+Aug 29 09:51:01 blizard kernel: current->tss.cr3 = 0062d000, ^Pr3 = 0062d000
+Aug 29 09:51:01 blizard kernel: *pde = 00000000
+Aug 29 09:51:01 blizard kernel: Oops: 0002
+Aug 29 09:51:01 blizard kernel: CPU:    0
+Aug 29 09:51:01 blizard kernel: EIP:    0010:[oops:_oops+16/3868]
+Aug 29 09:51:01 blizard kernel: EFLAGS: 00010212
+Aug 29 09:51:01 blizard kernel: eax: 315e97cc   ebx: 003a6f80   ecx: 001be77b   edx: 00237c0c
+Aug 29 09:51:01 blizard kernel: esi: 00000000   edi: bffffdb3   ebp: 00589f90   esp: 00589f8c
+Aug 29 09:51:01 blizard kernel: ds: 0018   es: 0018   fs: 002b   gs: 002b   ss: 0018
+Aug 29 09:51:01 blizard kernel: Process oops_test (pid: 3374, process nr: 21, stackpage=00589000)
+Aug 29 09:51:01 blizard kernel: Stack: 315e97cc 00589f98 0100b0b4 bffffed4 0012e38e 00240c64 003a6f80 00000001 
+Aug 29 09:51:01 blizard kernel:        00000000 00237810 bfffff00 0010a7fa 00000003 00000001 00000000 bfffff00 
+Aug 29 09:51:01 blizard kernel:        bffffdb3 bffffed4 ffffffda 0000002b 0007002b 0000002b 0000002b 00000036 
+Aug 29 09:51:01 blizard kernel: Call Trace: [oops:_oops_ioctl+48/80] [_sys_ioctl+254/272] [_system_call+82/128] 
+Aug 29 09:51:01 blizard kernel: Code: c7 00 05 00 00 00 eb 08 90 90 90 90 90 90 90 90 89 ec 5d c3 
+---------------------------------------------------------------------------
+
+Dr. G.W. Wettstein           Oncology Research Div. Computing Facility
+Roger Maris Cancer Center    INTERNET: greg@wind.rmcc.com
+820 4th St. N.
+Fargo, ND  58122
+Phone: 701-234-7556