[PATCH] Determine the linux loader command at runtime

[PATCH] Determine the linux loader command at runtime

[Lubomir Rintel]

There are numerous ways to load Linux kernel depending on the platform customs.
Pick the correct one at runtime, so that legacy platform interfaces don't break
and newer platforms use their native ways of bootstrapping Linux.

Originally from Vladimir Serbinenko <phcoder@gmail.com>, slightly modified.
---
 ChangeLog               |  5 +++++
 util/grub.d/10_linux.in | 17 +++++++++++++++--
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 10abfe2..4f1ee02 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2014-01-20  Lubomir Rintel  <lkundrak@v3.sk>
+
+	* util/grub.d/10_linux.in: Determine the loader command by platform.
+	(linux_entry): Use the command appropriate for given platform.
+
 2014-01-19  Colin Watson  <cjwatson@ubuntu.com>
 
 	* grub-core/osdep/freebsd/hostdisk.c (grub_util_fd_open): Ignore
diff --git a/util/grub.d/10_linux.in b/util/grub.d/10_linux.in
index 00d1931..d980d9a 100644
--- a/util/grub.d/10_linux.in
+++ b/util/grub.d/10_linux.in
@@ -129,14 +129,14 @@ linux_entry ()
   message="$(gettext_printf "Loading Linux %s ..." ${version})"
   sed "s/^/$submenu_indentation/" << EOF
 	echo	'$(echo "$message" | grub_quote)'
-	linux	${rel_dirname}/${basename} root=${linux_root_device_thisversion} ro ${args}
+	\$linux	${rel_dirname}/${basename} root=${linux_root_device_thisversion} ro ${args}
 EOF
   if test -n "${initrd}" ; then
     # TRANSLATORS: ramdisk isn't identifier. Should be translated.
     message="$(gettext_printf "Loading initial ramdisk ...")"
     sed "s/^/$submenu_indentation/" << EOF
 	echo	'$(echo "$message" | grub_quote)'
-	initrd	${rel_dirname}/${initrd}
+	\$initrd	${rel_dirname}/${initrd}
 EOF
   fi
   sed "s/^/$submenu_indentation/" << EOF
@@ -169,6 +169,19 @@ prepare_root_cache=
 boot_device_id=
 title_correction_code=
 
+# Pick a correct kernel load command. Use real mode entry point on legacy PC
+# platform (so that EDD and APM keep being available) and native entry point
+# on everything else.
+cat <<EOF
+if [ x\$grub_platform = xpc ]; then
+	linux=linux16
+	initrd=initrd16
+else
+	linux=linux
+	initrd=initrd
+fi
+EOF
+
 # Extra indentation to add to menu entries in a submenu. We're not in a submenu
 # yet, so it's empty. In a submenu it will be equal to '\t' (one tab).
 submenu_indentation=""
-- 
1.8.5.3

Re: [PATCH] Determine the linux loader command at runtime

[Colin Watson]

On Thu, Jan 30, 2014 at 09:24:42AM +0100, Lubomir Rintel wrote:
> There are numerous ways to load Linux kernel depending on the platform customs.
> Pick the correct one at runtime, so that legacy platform interfaces don't break
> and newer platforms use their native ways of bootstrapping Linux.

We (Ubuntu) have been using the 32-bit entry point on i386-pc for quite
some time, and I'm fairly sure we rely on it to make gfxpayload work for
flicker-free boot.  It looks like this will break that; please don't.

-- 
Colin Watson                                       [cjwatson@ubuntu.com]