mcelog: Add kernel CONFIG message if /dev/mcelog isn't found

Linux kernel made support for /dev/mcelog optional in v4.12. Most
distributions built with CONFIG_X86_MCELOG_LEGACY=y for a while.
But some have started to drop it.

When /dev/mcelog cannot be opened, provide an extra message to tell
users to check if their kernel is built with this option.

Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/mcelog.c b/mcelog.c
index 40d4bad..dc6e8a6 100644
--- a/mcelog.c
+++ b/mcelog.c
@@ -1383,6 +1383,7 @@ int main(int ac, char **av)
 		if (ignore_nodev) 
 			exit(0);
 		SYSERRprintf("Cannot open `%s'", logfn);
+		SYSERRprintf("Is your kernel built with CONFIG_X86_MCELOG_LEGACY=y?");
 		exit(1);
 	}