grub issues message at boot - "error - can't find command hwmatch"

Question

This question Error unknown command hwmatch is exactly what I'm asking but was closed as non reproducible. Mine is very reproducible.

Ubuntu 18.04 freshly installed on a 64-bit UEFI machine. Default grub boot options work fine, but I wanted to add a brief countdown (my normal config). After editing /etc/default/grub as normal and running sudo update-grub, the countdown works, but I get the error shown in the question title.

I tried the solution (copying files) in the closed question but it didn't seem to fit my configuration. Frankly I found the answer confusing.

I also tried editing /etc/grub.d/10_linux to comment out the IF-THEN structure that uses hwmatch. After that I did a sudo update-grub but I still got the error.

How can I get my countdown and not see this error?

Edit per comments -

Stock grub as installed (all non-commented-out lines shown)

GRUB_DEFAULT=0
GRUB_TIMEOUT_STYLE=hidden
GRUB_TIMEOUT=0
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""

Edited grub to give countdown (all non-commented-out lines shown)

GRUB_DEFAULT=0
GRUB_TIMEOUT_STYLE=countdown
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""

Edit your question and show us cat /etc/default/grub. Tell me what you edited/added to enable countdown. — heynnema, Sep 15 '19 at 20:17
Did you ever add an "insmod hwmatch" anywhere in the grub.d files? — ubfan1, Sep 15 '19 at 20:46
@OrganicMarble show me the other grub lines that are not commented out. — heynnema, Sep 15 '19 at 20:57
hwmatch.mod is a module in the /boot/grub/i386-pc directory, and may need an explicit insmod somewhere before the use of hwmatch command in 10_linux. Pick a location in the executation path (not in a function) before the hwmatch command to add insmod hwmatch.. — ubfan1, Sep 15 '19 at 20:59
@heynnema these are all the grub lines that are not commented out. — Organic Marble, Sep 15 '19 at 21:00
@ubfan1 my system doesn't have that directory. /boot/grub only has fonts, locale, and x86_64-efi sub-directories. — Organic Marble, Sep 15 '19 at 21:08
@OrganicMarble set GRUB_GFXMODE=640x480 and sudo update-grub and retry. If that doesn't help... on the outside chance... try GRUB_DEFAULT=saved and GRUB_SAVEDEFAULT=true together, and sudo update-grub. — heynnema, Sep 15 '19 at 21:09
@heynnema I'm willing to try...but how is that going to replace the missing module? — Organic Marble, Sep 15 '19 at 21:09
@heynnema that just gave me a much larger font reading of error - can't find module hwmatch — Organic Marble, Sep 15 '19 at 21:14
OK, I got it. Editing the 10_linux worked, but I made 10_linux_backup and that got incorporated into the cfg. I made 10_linux_backup not executable and it's working now. — Organic Marble, Sep 15 '19 at 21:21
The module hmwatch is part of the package gub-pc but not of grub-efi. Probably you should file a bug-report. For me your configuration works without error. — mook765, Sep 16 '19 at 04:10
@mook765 I went to report it and found it had been done already: https://bugs.launchpad.net/ubuntu/+source/grub2-signed/+bug/1840560 — Organic Marble, Sep 16 '19 at 15:22
@OrganicMarble I never heard back if you have the file /usr/gfxblacklist.txt, and if so, what its contents are. — heynnema, Sep 17 '19 at 14:14
@heynnema I'm happy with my fix for the problem and don't wish to investigate it further. — Organic Marble, Sep 17 '19 at 14:16

Levente · Accepted Answer · 2021-04-20T16:02:09.040

3

To get rid of the error message, add this line to /etc/default/grub:

GRUB_GFXPAYLOAD_LINUX=keep

Source: #4 comment on https://bugs.launchpad.net/ubuntu/+source/grub2-signed/+bug/1840560

This will let a condition in the code get evaluated in such way that the codeblock referencing hwmatch gets bypassed.

As to how worrying is the missing command (or not): according to mook765's comment, it's part of only grub-pc, and not grub-efi, and is supposedly being referenced as a mistake in the case of a grub-efi install.

A voluntary remark on the countdown / menu:

Using

GRUB_TIMEOUT_STYLE=menu

instead of

GRUB_TIMEOUT_STYLE=countdown

would make the menu visible (while leaving the countdown feature (at the bottom of the screen) and automatic fallback selection intact).

Don't forget to run sudo update-grub after being done with the editing.

edited Apr 20 '21 at 16:02

answered Dec 18 '20 at 13:25

Levente

3,961

I'm switching the accept to this answer instead of mine because it's the superior approach. I'm not sure why you added the part about displaying the grub menu though, I don't want that. I just want the 5 second countdown, and my config gives me that. – Organic Marble Apr 20 '21 at 15:47
1

@OrganicMarble Thank you for the accept. I have applied updates :) (I left in a smoothened variant of the menu visibility remark because I think there's still a lot of people after that kind of information.) – Levente Apr 20 '21 at 16:00

Organic Marble · Answer 2 · 2019-09-15T21:29:12.223

I commented out the if-then structure in /etc/grub.d/10_linux that used hwmatch and that worked.

Note this was a Brute Force and Ignorance fix because I didn't know which of the outcomes in the if-then structure to choose. The one I chose worked for me, it may not for you.

After running sudo update-grub I got the desired result on boot.

# Use ELILO's generic "efifb" when it's known to be available.
# FIXME: We need an interface to select vesafb in case efifb can't be used.
if [ "x$GRUB_GFXPAYLOAD_LINUX" != x ] || [ "$gfxpayload_dynamic" = 0 ]; then
  echo "set linux_gfx_mode=$GRUB_GFXPAYLOAD_LINUX"
else
  cat << EOF
if [ "\${recordfail}" != 1 ]; then
  if [ -e \${prefix}/gfxblacklist.txt ]; then
#    if hwmatch \${prefix}/gfxblacklist.txt 3; then
#      if [ \${match} = 0 ]; then
        set linux_gfx_mode=keep
#      else
#        set linux_gfx_mode=text
#      fi
#    else
#      set linux_gfx_mode=text
#    fi
  else
    set linux_gfx_mode=keep
  fi
else
  set linux_gfx_mode=text
fi
EOF
fi
cat << EOF
export linux_gfx_mode
EOF

Note: at first this didn't work because I copied /etc/grub.d/10_linux to /etc/grub.d/10_linux-backup before editing it. But all executable files in grub.d get picked up so the original one got copied in too. I'm fortunate the system booted. I took the executable setting away from /etc/grub.d/10_linux-backup, re-ran sudo update-grub, and that did it.

grub issues message at boot - "error - can't find command hwmatch"

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