Pkg xen devel - Aug 2022 - Bug#1016547: /etc/default/grub.d/xen.cfg: Extraneous output line causes error message at boot

Package: xen-hypervisor-common
Version: 4.14.5+24-g87d90d511c-1
Severity: minor
File: /etc/default/grub.d/xen.cfg

Dear Maintainer,

When invoked via grub-mkconfig, xen.cfg outputs this as its first line:
	Including Xen overrides from /etc/default/grub.d/xen.cfg

The output of grub-mkconfig is expected to be redirected into a grub.cfg file.
Grub will read the grub.cfg at boot. Unfortunately, "Including" is not
a
valid grub command. So when booting, grub emits this error message before
displaying its menu:
	error: can't find command `Including'.


The error message is obscured very quickly. It does not affect functionality
in any way. It requires booting on a VERY slow machine in order to read
the error message at all.


If I add a '#' to the start of the "Including", the resulting
grub config file
boots with no error.
	echo "#Including Xen overrides from /etc/default/grub.d/xen.cfg"


I'm not sure if this line was intended to go into the generated config
file as a comment, or if it was intended to be shown to the user while
grub-mkconfig is running.


I have observed this and tested my fix against version
4.14.5+24-g87d90d511c-1 of xen-hypervisor-common. I have also checked
with the debian git at
https://salsa.debian.org/xen-team/debian-xen/-/blob/master/debian/tree/xen-hypervisor-common/etc/default/grub.d/xen.cfg.
This line
has not changed in a very long time.


I can also duplicate the behavior using grub-emu, with the output redirected
to a file.


I am running devuan, and originally reported this to their BTS but was
redirected to debian. So my version number does not match. Apologies for
that.


Thanks for your time.

-Mag



-- System Information:
Debian Release: 10.0
Architecture: amd64 (x86_64)

Kernel: Linux 5.10.0-16-amd64 (SMP w/2 CPU threads)
Locale: LANG=C, LC_CTYPE=C.UTF-8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /bin/dash
Init: sysvinit (via /sbin/init)
LSM: AppArmor: enabled

-- Configuration Files:
/etc/default/grub.d/xen.cfg changed:
echo "#Including Xen overrides from /etc/default/grub.d/xen.cfg"
XEN_OVERRIDE_GRUB_DEFAULT=0
if [ "$XEN_OVERRIDE_GRUB_DEFAULT" = "" ]; then
	echo "WARNING: GRUB_DEFAULT changed to boot into Xen by default!"
	echo "         Edit /etc/default/grub.d/xen.cfg to avoid this
warning."
	XEN_OVERRIDE_GRUB_DEFAULT=1
fi
if [ "$XEN_OVERRIDE_GRUB_DEFAULT" = "1" ]; then
	GRUB_DEFAULT=$( \
		printf "$(gettext "%s, with Xen hypervisor")" \
		"$GRUB_DISTRIBUTOR GNU/Linux")
fi


-- no debconf information

Hi John,

On 8/2/22 19:50, John E. Krokes wrote:
> Package: xen-hypervisor-common
> Version: 4.14.5+24-g87d90d511c-1
> Severity: minor
> File: /etc/default/grub.d/xen.cfg
> 
> Dear Maintainer,
> 
> When invoked via grub-mkconfig, xen.cfg outputs this as its first line:
> 	Including Xen overrides from /etc/default/grub.d/xen.cfg
> 
> The output of grub-mkconfig is expected to be redirected into a grub.cfg
file.
> Grub will read the grub.cfg at boot. Unfortunately, "Including"
is not a
> valid grub command. So when booting, grub emits this error message before
> displaying its menu:
> 	error: can't find command `Including'.
Aha! Nice catch. That's indeed something that should be improved.
> [...]
> 
> The error message is obscured very quickly. It does not affect
functionality
> in any way. It requires booting on a VERY slow machine in order to read
> the error message at all.
> 
> 
> If I add a '#' to the start of the "Including", the
resulting grub config file
> boots with no error.
> 	echo "#Including Xen overrides from /etc/default/grub.d/xen.cfg"
> 
> I'm not sure if this line was intended to go into the generated config
> file as a comment, or if it was intended to be shown to the user while
> grub-mkconfig is running.
I'm sure it's the latter, yes. Just some 'hey! I'm doing this
now' message.
> I have observed this and tested my fix against version
> 4.14.5+24-g87d90d511c-1 of xen-hypervisor-common. I have also checked
> with the debian git at
https://salsa.debian.org/xen-team/debian-xen/-/blob/master/debian/tree/xen-hypervisor-common/etc/default/grub.d/xen.cfg.
This line
> has not changed in a very long time.
> 
> 
> I can also duplicate the behavior using grub-emu, with the output
redirected
> to a file.
> 
> 
> I am running devuan, and originally reported this to their BTS but was
> redirected to debian. So my version number does not match. Apologies for
> that.
It's ok. The changes/improvements for this will end up in the Xen 4.16
package that's in Debian unstable now, anyway.

So, in our grub.d/xen.cfg file, there's two places that cause text
output: the 'Including Xen overrides ...' informational one, and the
notification/warning about overriding GRUB_DEFAULT.

The grub.d/* files are executed (sourced) in the context of the
grub-mkconfig itself using '.'. In there, I can see that similar status
messages are just redirected to stderr. We can do the same here. For the
warning, there's a grub_warn helper function, which we can use.

So, that results in the follow changes I have here now:

diff --git a/default/grub.d/xen.cfg b/default/grub.d/xen.cfg
index d35744e..42670eb 100644
--- a/default/grub.d/xen.cfg
+++ b/default/grub.d/xen.cfg
@@ -5,7 +5,7 @@
 # The configuration in here makes it possible to have different options set
 # for the linux kernel when booting with or without Xen.

-echo "Including Xen overrides from /etc/default/grub.d/xen.cfg"
+echo "Including Xen overrides from /etc/default/grub.d/xen.cfg"
>&2

 #######################################################################
 # Xen Hypervisor Command Line Options
@@ -83,8 +83,8 @@ GRUB_CMDLINE_LINUX_XEN_REPLACE="earlyprintk=xen
console=hvc0 noresume"
 #XEN_OVERRIDE_GRUB_DEFAULT #
 if [ "$XEN_OVERRIDE_GRUB_DEFAULT" = "" ]; then
-       echo "WARNING: GRUB_DEFAULT changed to boot into Xen by
default!"
-       echo "         Edit /etc/default/grub.d/xen.cfg to avoid this
warning."
+       grub_warn "GRUB_DEFAULT changed to boot into Xen by default!"
\
+                 "Edit /etc/default/grub.d/xen.cfg to avoid this
warning."
        XEN_OVERRIDE_GRUB_DEFAULT=1
 fi
 if [ "$XEN_OVERRIDE_GRUB_DEFAULT" = "1" ]; then

None of this output will now be mixed with the generated config any more.

This will be in the next package upload.

https://salsa.debian.org/xen-team/debian-xen/-/commits/wip/sid

Thanks,
Hans

Your message dated Tue, 23 Aug 2022 12:34:36 +0000
with message-id <E1oQT76-005gaQ-Os at fasolo.debian.org>
and subject line Bug#1016547: fixed in xen 4.16.2-1
has caused the Debian Bug report #1016547,
regarding /etc/default/grub.d/xen.cfg: Extraneous output line causes error
message at boot
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.

(NB: If you are a system administrator and have no idea what this
message is talking about, this may indicate a serious mail system
misconfiguration somewhere. Please contact owner at bugs.debian.org
immediately.)


-- 
1016547: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1016547
Debian Bug Tracking System
Contact owner at bugs.debian.org with problems
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