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Re: [PATCH 2/2] grub2: use stat instead of udevadm for partition lookup

From: Paul Menzel
Subject: Re: [PATCH 2/2] grub2: use stat instead of udevadm for partition lookup
Date: Tue, 13 Jul 2021 11:25:49 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0

Dear Petr, dear Jeff,

Am 08.07.21 um 17:55 schrieb Petr Vorel:
From: Jeff Mahoney <>

sysfs_partition_path calls udevadm to resolve the sysfs path for
a block device. That can be accomplished by stating the device node
and using the major/minor to follow the symlinks in /sys/dev/block/.

This cuts the execution time of grub2-mkconfig from 10s to 2s on
my system.

Petr, where you able to reproduce this issue? Could the specifications of Jeff’s system be added to the commit message?

Signed-off-by: Jeff Mahoney <>
[ pvorel: include grub/osdep/major.h ]
Signed-off-by: Petr Vorel <>
  grub-core/osdep/linux/hostdisk.c | 8 ++++++++
  1 file changed, 8 insertions(+)

diff --git a/grub-core/osdep/linux/hostdisk.c b/grub-core/osdep/linux/hostdisk.c
index da62f924e..43dc4b0ba 100644
--- a/grub-core/osdep/linux/hostdisk.c
+++ b/grub-core/osdep/linux/hostdisk.c
@@ -31,6 +31,7 @@
  #include <grub/misc.h>
  #include <grub/i18n.h>
  #include <grub/list.h>
+#include <grub/osdep/major.h>
#include <stdio.h>
  #include <stdlib.h>
@@ -105,6 +106,13 @@ sysfs_partition_path (const char *dev, const char *entry)
    char *buf = NULL;
    size_t len = 0;
    char *path = NULL;
+  struct stat st;
+  int ret;
+  ret = stat(dev, &st);
+  if (ret == 0 && S_ISBLK(st.st_mode))
+    return xasprintf ("/sys/dev/block/%u:%u/%s",
+                     major (st.st_rdev), minor (st.st_rdev), entry);
argv[0] = "udevadm";
    argv[1] = "info";

Now the non-block device case has one stat call more executed each time.

Kind regards,


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