Allow complete override of MODULES_*

The long-standing but undocumented AMODULES_* options allow adding
ADDITIONAL modules during boot, but there was no way to completely
override the MODULES_* variables.

Add this functionality now, and document it in genkernel.conf.

Fixes: https://bugs.gentoo.org/show_bug.cgi?id=186652
Signed-off-by: Robin H. Johnson <robbat2@gentoo.org>

2 files changed, 24 insertions, 3 deletions

diff --git a/genkernel b/genkernel
index eeaf5dd1..444c559f 100755
--- a/genkernel
+++ b/genkernel
@@ -105,16 +105,30 @@ echo
 # Set ${ARCH}
 get_official_arch
 
-# Read arch-specific config
 print_info 1 "Using genkernel.conf from ${_GENKERNEL_CONF}"
+# Save any customizations of MODULES_* first.
+override_module_vars="$(compgen -A variable |grep '^MODULES_')"
+for v in $override_module_vars ; do
+	print_info 1 "Saving $v to override defaults"
+	newvar=override_$v
+	eval "${newvar}='${!v}'"
+done
+
+# Read arch-specific config
 print_info 1 "Sourcing arch-specific config.sh from ${ARCH_CONFIG} .."
 source ${ARCH_CONFIG} || gen_die "Could not read ${ARCH_CONFIG}"
 _MODULES_LOAD=${GK_SHARE}/arch/${ARCH}/modules_load
 print_info 1 "Sourcing arch-specific modules_load from ${_MODULES_LOAD} .."
 source "${_MODULES_LOAD}" || gen_die "Could not read ${_MODULES_LOAD}"
-echo
 
-# Merge modules_load from config
+# Now apply customizations of MODULES_*
+for v in $override_module_vars; do
+	newvar=override_$v
+	print_info 1 "Override $v, default (${!v}), new value (${!newvar})"
+	eval "${v}='${!newvar}'"
+done
+
+# Merge additional modules_load from config
 for group_modules in ${!AMODULES_*}; do
 	group="$(echo $group_modules | cut -d_ -f2)"
 	eval cmodules="\$$group_modules"
diff --git a/genkernel.conf b/genkernel.conf
index 9ff7e4ff..10a03bc4 100644
--- a/genkernel.conf
+++ b/genkernel.conf
@@ -300,6 +300,13 @@ DEFAULT_KERNEL_SOURCE="/usr/src/linux"
 # Use this with caution.
 #AMODULES_group="module-to-include another-module"
 
+# Override the default modules in the ramdisk, for a given group, as defined by
+# /usr/share/genkernel/default/modules_load and the per-arch modules_load
+# files. You PROBABLY want to use AMODULES_* above, and NOT MODULES_* here.
+# If you use MODULES_* here, the default and per-arch modules will NOT be used.
+#MODULES_group1="some-module"
+#MODULES_group2="" # Load no modules for this group
+
 # File to output a .tar.bz2'd modules after the
 # callbacks have run
 #MODULESPACKAGE="/path/to/file.bz2"