From: Neil Horman <nhorman@redhat.com>
Date: Thu, 10 Jan 2008 13:51:09 -0500
Subject: [xen] kdump: fix dom0 /proc/vmcore layout
Message-id: 20080110185109.GE4486@hmsendeavour.rdu.redhat.com
O-Subject: [PATCH 5.2] fix dom0 /proc/vmcore layout
Bugzilla: 423731

Hey-
	Recently found that kdump on dom0 kernels results in a vmcore file that
has a bogus notes section in it, which prevents crash from reading it.  This is
an artifact of the inclusion of /sys/kernel/vmcoreinfo support.  Apparently we
cant currently obtain the apprpriate info from dom0 kernels to format the
vmcoreinfo section in the crash file properly:
http://lists.infradead.org/pipermail/kexec/2007-September/000790.html
Best solution at this moment I think is this patch, which removes
/sys/kernel/vmcoreinfo from dom0 kernels.  I've tested this and it allows us to
produce readable crashdumps in a dom0 environment.  The only side effect is,
without /sys/kernel/vmcoreinfo present, the makedumpfile dump filtering utility
requires a kernels debuginfo pacakge to be installed.  Basically if you use
makedumpfile in kdump, then you also need to install debuginfo on dom0 kernels.
I think thats a pretty reasonable tradeoff though until we fix vmcoreinfo
properly upstream.  Fixes bz 423731

Regards
Neil

Acked-by: Dave Anderson <anderson@redhat.com>
Acked-by: Jarod Wilson <jwilson@redhat.com>
Acked-by: "Stephen C. Tweedie" <sct@redhat.com>

diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index 6ea6c10..121dfe1 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -61,6 +61,7 @@ static ssize_t kexec_crash_loaded_show(struct subsystem *subsys, char *page)
 }
 KERNEL_ATTR_RO(kexec_crash_loaded);
 
+#ifndef CONFIG_XEN
 static ssize_t vmcoreinfo_show(struct kset *kset, char *page)
 {
 	return sprintf(page, "%lx %x\n",
@@ -68,6 +69,7 @@ static ssize_t vmcoreinfo_show(struct kset *kset, char *page)
 		       (unsigned int)vmcoreinfo_max_size);
 }
 KERNEL_ATTR_RO(vmcoreinfo);
+#endif /* CONFIG_XEN */
 
 #endif /* CONFIG_KEXEC */
 
@@ -82,8 +84,10 @@ static struct attribute * kernel_attrs[] = {
 #ifdef CONFIG_KEXEC
 	&kexec_loaded_attr.attr,
 	&kexec_crash_loaded_attr.attr,
+#ifndef CONFIG_XEN
 	&vmcoreinfo_attr.attr,
-#endif
+#endif /* CONFIG_XEN */
+#endif /* CONFIG_KEXEC */
 	NULL
 };