[Crash-utility] Re: 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