[Crash-utility] linux_banner problem in 2.6.20/Ubuntu
Hi Dave,
trying the latest crash-4.0-3.20 on the latest Ubuntu/feisty kernel
2.6.20-9-generic I have found that live access does not work because of the
following mismatch:
/proc/version:
Linux version 2.6.20-9-generic (root@rothera) (gcc version 4.1.2 (Ubuntu
4.1.2-0ubuntu3)) #2 SMP Mon Feb 26 03:01:44 UTC 2007
linux_banner:
Linux version 2.6.20-9-generic (root@rothera) (gcc version 4.1.2 (Ubuntu
4.1.2-0ubuntu3)) #2 SMP Mon Feb 26 03:01:44 UTC 2007 (Ubuntu
2.6.20-9.16-generic)
Looking at 2.6.20 sources (as provided in Ubuntu package) we see:
----------------------------------------------------------------------------------------
const char linux_banner[] =
"Linux version " UTS_RELEASE " (" LINUX_COMPILE_BY "@"
LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION
#ifdef CONFIG_VERSION_SIGNATURE
" (" CONFIG_VERSION_SIGNATURE ")"
#endif
"\n";
const char linux_proc_banner[] =
"%s version %s"
" (" LINUX_COMPILE_BY "@" LINUX_COMPILE_HOST ")"
" (" LINUX_COMPILER ") %s\n";
----------------------------------------------------------------------------------------
As a result, these two strings will be different if CONFIG_VERSION_SIGNATURE
is defined as non-empty string.
The comparison crash uses is (kernel.c):
if (strlen(kt->proc_version) && !STREQ(buf, kt->proc_version))
{
if (CRASHDEBUG(1)) {
fprintf(fp, "/proc/version:\n%s",
kt->proc_version);
fprintf(fp, "linux_banner:\n%s\n", buf);
}
goto bad_match;
I tried to fix the problem by replacing STREQ with STRNEQ. Unfortunately, this
does not work as both strings are LF-terminated. So I had to use
--- kernel.c.orig 2007-02-21 15:52:01.000000000 -0500
+++ kernel.c 2007-03-11 08:20:38.468024104 -0400
@@ -498,7 +498,8 @@
error(WARNING, "cannot read linux_banner string\n");
if (ACTIVE()) {
- if (strlen(kt->proc_version) && !STREQ(buf,
kt->proc_version))
{
+ int cmplen = strlen(kt->proc_version)-1;
+ if (cmplen>0 && strncmp(buf, kt->proc_version, cmplen) != 0)
{
if (CRASHDEBUG(1)) {
fprintf(fp, "/proc/version:\n%s",
kt->proc_version);
Please note that this seems to be Ubuntu-specific problem - the generic
2.6.20.2 has linux_banner definition without CONFIG_VERSION_SIGNATURE.
Searching Google for "linux CONFIG_VERSION_SIGNATURE" I can see only results
related to Ubuntu.
Regards,
Alex