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List:       busybox
Subject:    [PATCH] [1/2] modprobe: Add -S option to use a different kernel version
From:       Jeff Pohlmeyer <yetanothergeek () gmail ! com>
Date:       2024-02-07 13:55:03
Message-ID: CAEuRe+3RmNdK0Nw43Nofo6a4oZdsVcA+Y+3HwCvJDP2zinNg9A () mail ! gmail ! com
[Download RAW message or body]

(These two patches are somewhat related but do not depend on each other and
can be applied separately.)

Support -S to use another kernel version (66 bytes)

Normally modprobe will use version information from the currently running
kernel (similar to `uname -r`). This patch adds a compile-time configuration
option to enable the -S switch, which allows specifying a different kernel
version. This can be useful when used with the -D option to determine module
dependencies when building a new initramfs after a kernel upgrade.


function                                             old     new   delta
packed_usage                                       34776   34812     +36
modprobe_main                                        946     974     +28
.rodata                                           103911  103913      +2
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/0 up/down: 66/0)               Total: 66 bytes
   text       data        bss        dec        hex    filename
1180482       7435       4984    1192901     1233c5    busybox_old
1180548       7435       4984    1192967     123407    busybox_unstripped

["modprobe-add-set-version-option.patch" (text/x-patch)]

From c724000013e2b185d63b9adf969fe771033d5908 Mon Sep 17 00:00:00 2001
From: Jeff Pohlmeyer <yetanothergeek@gmail.com>
Date: Fri, 2 Feb 2024 06:18:52 -0600
Subject: [PATCH] modprobe: Add -S option to use a different kernel version

---
 modutils/modprobe.c | 25 +++++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/modutils/modprobe.c b/modutils/modprobe.c
index 543f53e99..8bec5ffb0 100644
--- a/modutils/modprobe.c
+++ b/modutils/modprobe.c
@@ -24,6 +24,17 @@
 //config:	blacklisted modules. This is useful if you want to prevent your
 //config:	hardware autodetection scripts to load modules like evdev, frame
 //config:	buffer drivers etc.
+//config:config FEATURE_MODPROBE_SET_VER
+//config:	bool "Support -S to use another kernel version (66 bytes)"
+//config:	default n
+//config:	depends on MODPROBE && !MODPROBE_SMALL
+//config:	help
+//config:	Normally modprobe will use version information from the currently
+//config:	running kernel (a la `uname -r`). Say 'y' here to enable the -S
+//config:	option, which will allow specifying a different kernel version.
+//config:	This can be useful in conjunction with the -D option to determine
+//config:	module dependencies when building a new initramfs after a kernel
+//config:	upgrade.
 
 //applet:IF_MODPROBE(IF_NOT_MODPROBE_SMALL(APPLET_NOEXEC(modprobe, modprobe, \
BB_DIR_SBIN, BB_SUID_DROP, modprobe)))  
@@ -110,7 +121,7 @@
 //usage:       "   from the command line\n"
 //usage:
 //usage:#define modprobe_trivial_usage
-//usage:	"[-alrqvsD" IF_FEATURE_MODPROBE_BLACKLIST("b") "]"
+//usage:	"[-alrqvsD" IF_FEATURE_MODPROBE_BLACKLIST("b") \
IF_FEATURE_MODPROBE_SET_VER("S:") "]"  //usage:	" MODULE" \
IF_FEATURE_CMDLINE_MODULE_OPTIONS(" [SYMBOL=VALUE]...")  //usage:#define \
modprobe_full_usage "\n\n"  //usage:       "	-a	Load multiple MODULEs"
@@ -123,6 +134,9 @@
 //usage:	IF_FEATURE_MODPROBE_BLACKLIST(
 //usage:     "\n	-b	Apply blacklist to module names too"
 //usage:	)
+//usage:	IF_FEATURE_MODPROBE_SET_VER(
+//usage:     "\n	-S VERSION	Use kernel VERSION"
+//usage:	)
 //usage:#endif /* !ENABLE_MODPROBE_SMALL */
 
 /* Note: usage text doesn't document various 2.4 options
@@ -130,7 +144,7 @@
  * Note2: -b is always accepted, but if !FEATURE_MODPROBE_BLACKLIST,
  * it is a no-op.
  */
-#define MODPROBE_OPTS  "alrDb"
+#define MODPROBE_OPTS  "alrDb" IF_FEATURE_MODPROBE_SET_VER("S:")
 /* -a and -D _are_ in fact compatible */
 #define MODPROBE_COMPLEMENTARY "q-v:v-q:l--arD:r--alD:a--lr:D--rl"
 //#define MODPROBE_OPTS  "acd:lnrt:C:b"
@@ -147,6 +161,7 @@ enum {
 	//OPT_CONFIGFILE = (INSMOD_OPT_UNUSED << x), /* C */
 	OPT_SHOW_DEPS    = (INSMOD_OPT_UNUSED << 3), /* D */
 	OPT_BLACKLIST    = (INSMOD_OPT_UNUSED << 4) * ENABLE_FEATURE_MODPROBE_BLACKLIST,
+	OPT_SET_VER      = (INSMOD_OPT_UNUSED << 5) * ENABLE_FEATURE_MODPROBE_SET_VER,
 };
 #if ENABLE_LONG_OPTS
 static const char modprobe_longopts[] ALIGN1 =
@@ -559,18 +574,24 @@ int modprobe_main(int argc UNUSED_PARAM, char **argv)
 	int rc;
 	unsigned opt;
 	struct module_entry *me;
+	IF_FEATURE_MODPROBE_SET_VER(const char *version;)
 
 	INIT_G();
 
 	opt = getopt32long(argv, "^" INSMOD_OPTS MODPROBE_OPTS "\0" MODPROBE_COMPLEMENTARY,
 			modprobe_longopts
 			INSMOD_ARGS
+			IF_FEATURE_MODPROBE_SET_VER(, &version)
 	);
 	argv += optind;
 
 	/* Goto modules location */
 	xchdir(CONFIG_DEFAULT_MODULES_DIR);
 	uname(&G.uts);
+	IF_FEATURE_MODPROBE_SET_VER(
+		if (opt & OPT_SET_VER)
+			safe_strncpy(G.uts.release, version, sizeof(G.uts.release));
+	)
 	xchdir(G.uts.release);
 
 	if (opt & OPT_LIST_ONLY) {
-- 
2.43.0



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