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RE: SystemTap vs. FC5 Xen kernels (was: 03-23-2006 Meeting minutes)
- From: "Stone, Joshua I" <joshua dot i dot stone at intel dot com>
- To: "William Cohen" <wcohen at redhat dot com>, "Roland McGrath" <roland at redhat dot com>
- Cc: "SystemTap" <systemtap at sources dot redhat dot com>
- Date: Thu, 30 Mar 2006 13:17:58 -0800
- Subject: RE: SystemTap vs. FC5 Xen kernels (was: 03-23-2006 Meeting minutes)
Stone, Joshua I wrote:
> I found two differences in the config files that will prevent
> SystemTap from running on the Xen kernels. In 2054_FC5 and
> 2054_FC5kdump, the config files have:
>
> CONFIG_KPROBES=y
> ...
> CONFIG_DEBUG_INFO=y
>
> Whereas in 2054_FC5xen0 and 2054_xenU, the config files have:
>
> # CONFIG_KPROBES is not set
>
> ... with no mention of CONFIG_DEBUG_INFO. This might explain the
> missing dwarf info in the kernel-debuginfo package. And of course for
> SystemTap we need CONFIG_KPROBES=y.
I believe I've found the root-cause for the missing debuginfo -
linux-2.6-xen.patch has this hunk:
diff -Nru -p --exclude='.*' ref-linux-2.6.16-rc5/lib/Kconfig.debug
linux-2.6.16-rc5-xen0/lib/Kconfig.debug
--- ref-linux-2.6.16-rc5/lib/Kconfig.debug 2006-03-01
11:12:31.000000000 -0500
+++ linux-2.6.16-rc5-xen0/lib/Kconfig.debug 2006-03-01
11:09:38.000000000 -0500
@@ -145,7 +145,7 @@ config DEBUG_BUGVERBOSE
config DEBUG_INFO
bool "Compile the kernel with debug info"
- depends on DEBUG_KERNEL
+ depends on DEBUG_KERNEL && !X86_64_XEN
help
If you say Y here the resulting kernel image will include
debugging info resulting in a larger kernel image.
Also, the same patch has this chunk at the top of
arch/x86_64/kernel/entry-xen.S:
+#ifdef CONFIG_DEBUG_INFO
+#undef CONFIG_DEBUG_INFO
+#endif
I'll leave open the question of *why* DEBUG_INFO is explicitly
disabled...
Josh