It's always bothered me that for some time (perhaps as long as I have
been using LFS?) that I could not get the kernel symbols properly loaded
by sysklogd, producing a message sequence like this:
Nov 15 15:45:38 www kernel: klogd 1.5.1, log source = /proc/kmsg
started.
Nov 15 15:45:38 www kernel: Inspecting /boot/System.map-5.9.8
Nov 15 15:45:38 www kernel: Cannot find map file.
It's a very minor nuisance, but I didn't like it.
It turns out that sysklogd inspects the System.map file but cannot find
a particular symbol, one named Version_XXXXXX, where XXXXXX is the
encoded Linux version number that corresponds to this map file.
It further turns out that init/version.c is not producing this symbol if
CONFIG_KALLSYMS is define. Since it usually IS defined (and kind of
should be, at this point), then this doesn't work.
I am certainly not a kernel expert, but as far as I can see, there's no
downside to producing this symbol anyway - even if CONFIG_KALLSYMS is
defined.
So I removed the check for CONFIG_KALLSYMS not being defined, with this
patch included at the end of this email.
When I boot this kernel, I get the following result:
Nov 16 06:28:51 www kernel: Inspecting /boot/System.map-5.9.8
Nov 16 06:28:51 www kernel: Loaded 116685 symbols from
/boot/System.map-5.9.8.
Nov 16 06:28:51 www kernel: Symbols match kernel version 5.9.8.
Again, I don't know if I am creating unintended side-effects by allowing
this symbol to be defined. I mean, there must have been SOME reason to
remove the generation of the "Version_" symbol if KALLSYMS is defined -
but I couldn't find it.
Thoughts?
-Joel
diff -Naur linux-5.9.8.orig/init/version.c linux-5.9.8/init/version.c
--- linux-5.9.8.orig/init/version.c 2020-11-10 12:16:17.000000000
-0800
+++ linux-5.9.8/init/version.c 2020-11-16 06:15:48.559481272 -0800
@@ -16,13 +16,11 @@
#include <linux/version.h>
#include <linux/proc_ns.h>
-#ifndef CONFIG_KALLSYMS
#define version(a) Version_ ## a
#define version_string(a) version(a)
extern int version_string(LINUX_VERSION_CODE);
int version_string(LINUX_VERSION_CODE);
-#endif
struct uts_namespace init_uts_ns = {
.kref = KREF_INIT(2),
--
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