Implement minimal depmod-compatible applet for vx

- Added depmod.cpp to scan kernel module ELF files, read .modinfo, and emit metadata files.
- Implemented functionality to write binary trie indexes for libkmod/modprobe.
- Introduced command-line options for module processing.
- Created test script test_depmod.sh to verify help and version commands.

src/depmod/depmod.8

@@ -0,0 +1,69 @@
+.Dd July 8, 2026
+.Dt DEPMOD 8
+.Os
+.Sh NAME
+.Nm depmod
+.Nd generate Linux kernel module dependency metadata
+.Sh SYNOPSIS
+.Nm
+.Op Fl aAenvwVh
+.Op Fl b Ar basedir
+.Op Fl m Ar moduledir
+.Op Fl o Ar outdir
+.Op Fl C Ar config
+.Op Fl E Ar Module.symvers
+.Op Fl F Ar System.map
+.Op Fl P Ar prefix
+.Op Ar version
+.Op Ar module ...
+.Sh DESCRIPTION
+The
+.Nm
+applet scans Linux kernel modules below
+.Pa /lib/modules/<version>
+and writes the usual module metadata files, including
+.Pa modules.dep ,
+.Pa modules.alias ,
+.Pa modules.symbols ,
+and the matching kmod binary index files.
+.Pp
+This implementation is intentionally small and does not use libkmod.  It reads
+uncompressed modules plus gzip and zstd compressed modules.
+.Sh OPTIONS
+.Bl -tag -width Ds
+.It Fl a , Fl -all
+Scan all modules.  This is the default when no module files are named.
+.It Fl A , Fl -quick
+Exit without regenerating output when
+.Pa modules.dep
+is newer than the scanned modules.
+.It Fl b Ar basedir , Fl -basedir Ns = Ns Ar basedir
+Use
+.Ar basedir
+as the input root.
+.It Fl m Ar moduledir , Fl -moduledir Ns = Ns Ar moduledir
+Use a module directory other than
+.Pa /lib/modules .
+.It Fl o Ar outdir , Fl -outdir Ns = Ns Ar outdir
+Use
+.Ar outdir
+as the output root.
+.It Fl n , Fl -show , Fl -dry-run
+Print text output to standard output instead of writing files.
+.It Fl e , Fl -errsyms
+Warn about unresolved module dependencies and symbols.
+.It Fl P Ar prefix , Fl -symbol-prefix Ns = Ns Ar prefix
+Ignore an architecture symbol prefix while matching symbols.
+.It Fl V , Fl -version
+Print version information.
+.It Fl h , Fl -help
+Print usage information.
+.El
+.Sh COMPATIBILITY
+The options
+.Fl C ,
+.Fl E ,
+and
+.Fl F
+are accepted for command-line compatibility, but this implementation does not
+parse depmod.d configuration, Module.symvers, or System.map content.

src/main.c

@@ -41,6 +41,9 @@ int lspci_main(int argc, char *argv[]);
 #if VX_ENABLE_SETPCI
 int setpci_main(int argc, char *argv[]);
 #endif
+#if VX_ENABLE_DEPMOD
+int depmod_main(int argc, char *argv[]);
+#endif
 
 struct applet {
 	const char *name;
@@ -91,6 +94,9 @@ static const struct applet applets[] = {
 #if VX_ENABLE_SETPCI
 	{ "setpci", setpci_main },
 #endif
+#if VX_ENABLE_DEPMOD
+	{ "depmod", depmod_main },
+#endif
 };
 
 static const size_t n_applets = sizeof(applets) / sizeof(applets[0]);