[PATCH] Changes to 10_linux (based on grub2 1.98) to generate boot stanza for Xen hypervisor (fix for bug #30257)

* [PATCH] Changes to 10_linux (based on grub2 1.98) to generate boot  stanza for Xen hypervisor (fix for bug #30257)
@ 2010-06-26  0:34 Dante Cinco
  2010-06-27 14:31 ` Vladimir 'φ-coder/phcoder' Serbinenko
  0 siblings, 1 reply; 2+ messages in thread
From: Dante Cinco @ 2010-06-26  0:34 UTC (permalink / raw)
  To: grub-devel


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I have attached a patch that will add the capability in the 10_linux grub2
script to detect and generate boot stanzas in grub.cfg for Xen hypervisors
(if present). It relies on the presence of CONFIG_XEN_DOM0=y to identify
dom0 kernels and pairs them with each version of the hypervisor that is
present. It uses the multiboot command for the Xen hypervisor image and the
module command for the vmlinuz kernel and initrd.img. It also explicitly
sources /etc/default/grub to define a new Xen-only variable called
GRUB_CMDLINE_XEN_DEFAULT. The alternative is to export this in
/usr/sbin/grub-mkconfig like the other GRUB variables. It will also generate
a boot stanza for the dom0 kernel without the hypervisor (in case the
hypervisor is broken).

There is a GNU GRUB bug filed on this which is bug #30257: 10_linux ignores
xen hypervisor entries and dom0 kernels.

Here's an example of an actual Xen boot stanza. The dummy=dummy in the
vmlinuz line is needed due to some bug in GRUB or Xen. Without it, the boot
will hang or stop and hit the initramfs (BusyBox) prompt.

/boot/grub/grub.cfg:

menuentry 'xen-4.0 osa-dom0 , with Linux 2.6.32.15-xen' --class osa-dom0
--class gnu-linux --class gnu --class os {
recordfail
insmod lvm
insmod ext2
set root='(system-dom0_0)'
search --no-floppy --fs-uuid --set cc290394-fa2a-4e13-9024-3bc5a5b9215d
multiboot /boot/xen-4.0.gz  com1=115200,8n1 console=com1 dom0_mem=512M
dom0_max_vcpus=1 dom0_vcpus_pin=true  iommu=1,passthrough,no-intremap
 loglvl=all loglvl_guest=all loglevl=10 debug  apic=on
apic_verbosity=verbose  extra_guest_irqs=80 acpi=force numa=on
module /boot/vmlinuz-2.6.32.15-xen dummy=dummy
root=/dev/mapper/system-dom0_0 ro quiet  earlyprintk=xen loglevel=10 debug
acpi=force console=hvc0,115200n8
module /boot/initrd.img-2.6.32.15-xen
}

/etc/default/grub:

GRUB_CMDLINE_XEN_DEFAULT=" com1=115200,8n1 console=com1 dom0_mem=512M
dom0_max_vcpus=1 dom0_vcpus_pin=true  iommu=1,passthrough,no-intremap
 loglvl=all loglvl_guest=all loglevl=10 debug  apic=on
apic_verbosity=verbose  extra_guest_irqs=80 acpi=force numa=on"

- Dante Cinco

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10_linux grub2 script.
Index: Xen-Ubuntu-10.04/etc/grub.d/10_linux
===================================================================
diff -Naur Ubuntu-10.04/etc/grub.d/10_linux Xen-Ubuntu-10.04/etc/grub.d/10_linux

--- Ubuntu-10.04/etc/grub.d/10_linux	2010-06-24 12:53:56.000000000 -0700
+++ Xen-Ubuntu-10.04/etc/grub.d/10_linux	2010-06-25 15:09:47.000000000 -0700
@@ -66,10 +66,17 @@
   version="$2"
   recovery="$3"
   args="$4"
-  if ${recovery} ; then
-    title="$(gettext_quoted "%s, with Linux %s (recovery mode)")"
+  xen_path="$6"
+  xen_cmdline="$7"
+  if [ "x$xen_cmdline" != "x" ]; then
+    xen_title=${xen_path%.gz}
+    title="${xen_title#/boot/} $(gettext_quoted "%s, with Linux %s")"
   else
-    title="$(gettext_quoted "%s, with Linux %s")"
+    if ${recovery} ; then
+      title="$(gettext_quoted "%s, with Linux %s (recovery mode)")"
+    else
+      title="$(gettext_quoted "%s, with Linux %s")"
+    fi
   fi
   printf "menuentry '${title}' ${CLASS} {\n" "${os}" "${version}"
   cat << EOF
@@ -92,9 +99,18 @@
 	echo	'$(printf "$(gettext_quoted "Loading Linux %s ...")" ${version})'
 EOF
   fi
-  cat << EOF
+  if [ "x$xen_cmdline" != "x" ]; then
+    module_or_initrd="module"
+    cat << EOF
+	multiboot ${xen_path} ${xen_cmdline}
+	module	${rel_dirname}/${basename} dummy=dummy root=${linux_root_device_thisversion} ro ${args}
+EOF
+  else
+    module_or_initrd="initrd"
+    cat << EOF
 	linux	${rel_dirname}/${basename} root=${linux_root_device_thisversion} ro ${args}
 EOF
+  fi
   if [ "x$5" != "xquiet" ]; then
     cat << EOF
 	echo	'$(gettext_quoted "Loading initial ramdisk ...")'
@@ -102,7 +118,7 @@
   fi
   if test -n "${initrd}" ; then
     cat << EOF
-	initrd	${rel_dirname}/${initrd}
+	${module_or_initrd}	${rel_dirname}/${initrd}
 EOF
   fi
   cat << EOF
@@ -115,6 +131,9 @@
       done`
 prepare_boot_cache=
 
+# Need to source this because GRUB_CMDLINE_XEN_DEFAULT is not exported in /usr/sbin/grub-mkconfig
+. /etc/default/grub
+
 while [ "x$list" != "x" ] ; do
   linux=`version_find_latest $list`
   echo "Found linux image: $linux" >&2
@@ -141,6 +160,18 @@
     linux_root_device_thisversion=${GRUB_DEVICE}
   fi
 
+  linux_config=${rel_dirname}/config-${version}
+  if grep -q 'CONFIG_XEN_DOM0=y' $linux_config ; then
+    for xen_entry in /boot/xen-*.gz ; do
+      if [ ! -L $xen_entry ]; then
+        echo "  dom0 kernel and Xen hypervisor: $xen_entry" >&2
+        linux_entry "${OS}" "${version}" false \
+            "${GRUB_CMDLINE_LINUX} ${GRUB_CMDLINE_EXTRA} ${GRUB_CMDLINE_LINUX_DEFAULT}" \
+            quiet "${xen_entry}" "${GRUB_CMDLINE_XEN_DEFAULT}"
+      fi
+    done
+  fi
+
   linux_entry "${OS}" "${version}" false \
       "${GRUB_CMDLINE_LINUX} ${GRUB_CMDLINE_EXTRA} ${GRUB_CMDLINE_LINUX_DEFAULT}" \
       quiet

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