tests: introduce vars to create kernel comps for nested

Introduce NESTED_COMP_KERNEL_MODULE_NAME and
NESTED_KERNEL_MODULES_COMP env vars. If present, a kernel-modules
component containing the specified kernel module will be created and
will be added when building the nested test image.

Author: alfonsosanchezbeato

tests/lib/nested.sh

@@ -921,6 +921,9 @@ nested_create_core_vm() {
             for mycomp in $(nested_get_extra_comps); do
                 EXTRA_SNAPS="$EXTRA_SNAPS --comp $mycomp"
             done
+            if [ -n "$NESTED_KERNEL_MODULES_COMP" ]; then
+                EXTRA_SNAPS="$EXTRA_SNAPS --comp pc-kernel+${NESTED_KERNEL_MODULES_COMP}.comp"
+            fi
 
             # only set SNAPPY_FORCE_SAS_URL because we don't need it defined 
             # anywhere else but here, where snap prepare-image as called by 

tests/lib/prepare.sh

@@ -922,6 +922,40 @@ uc20_build_initramfs_kernel_snap() {
     rm -rf repacked-kernel
 }
 
+
+# Modify kernel and create a component, kernel content expected in pc-kernel
+build_kernel_with_comp() {
+    mod_name=$1
+    comp_name=$2
+
+    kern_ver=$(find pc-kernel/modules/* -maxdepth 0 -printf "%f\n")
+    comp_ko_dir=$comp_name/modules/"$kern_ver"/kmod/
+    mkdir -p "$comp_ko_dir"
+    mkdir -p "$comp_name"/meta/
+    cat << EOF > "$comp_name"/meta/component.yaml
+component: pc-kernel+$comp_name
+type: kernel-modules
+version: 1.0
+summary: kernel component
+description: kernel component for testing purposes
+EOF
+    # Replace _ or - with [_-], as it can be any of these
+    glob_mod_name=$(printf '%s' "$mod_name" | sed -r 's/[-_]/[-_]/g')
+    module_path=$(find pc-kernel -name "${glob_mod_name}.ko*")
+    cp "$module_path" "$comp_ko_dir"
+    snap pack --filename=pc-kernel+"$comp_name".comp "$comp_name"
+
+    # remove the kernel module from the kernel snap
+    rm "$module_path"
+    # depmod wants a lib subdir, fake it and remove after invocation
+    mkdir pc-kernel/lib
+    ln -s ../modules pc-kernel/lib/modules
+    depmod -b pc-kernel/ "$kern_ver"
+    rm -rf pc-kernel/lib
+    # append component meta-information
+    printf 'components:\n  %s:\n    type: kernel-modules\n' "$comp_name" >> pc-kernel/meta/snap.yaml
+}
+
 uc24_build_initramfs_kernel_snap() {
     local ORIG_SNAP="$1"
     local TARGET="$2"
@@ -937,6 +971,11 @@ uc24_build_initramfs_kernel_snap() {
     unsquashfs -d pc-kernel "$ORIG_SNAP"
     objcopy -O binary -j .initrd pc-kernel/kernel.efi initrd.img
 
+    if [ -n "$NESTED_KERNEL_MODULES_COMP" ]; then
+        # "split" kernel in kernel-modules component and kernel
+        build_kernel_with_comp "$NESTED_COMP_KERNEL_MODULE_NAME" "$NESTED_KERNEL_MODULES_COMP"
+    fi
+
     unmkinitramfs initrd.img initrd
 
     if [ -d ./extra-initrd ]; then

tests/nested/manual/uc20-install-in-initrd/task.yaml

@@ -36,6 +36,10 @@ environment:
   NESTED_UBUNTU_IMAGE_SNAPPY_FORCE_SAS_URL: http://localhost:11028
   NESTED_SNAPD_DEBUG_TO_SERIAL: true
 
+  # create a kernel-modules component for efi-pstore
+  NESTED_KERNEL_MODULES_COMP: efi-pstore
+  NESTED_COMP_KERNEL_MODULE_NAME: efi-pstore
+
 prepare: |
   "$TESTSTOOLS"/store-state setup-fake-store "$NESTED_FAKESTORE_BLOB_DIR"
   cp "$TESTSLIB"/assertions/developer1.account "$NESTED_FAKESTORE_BLOB_DIR"/asserts
@@ -75,6 +79,30 @@ execute: |
 
   MATCH "mode=run" <modeenv
 
+  check_efi_pstore() {
+      # Compare times to check that drivers tree was created on
+      # installation, not on seeding
+      # shellcheck disable=SC2016
+      tree_birth=$(remote.exec 'date -d"$(stat --printf="%w\n" /var/lib/snapd/kernel/pc-kernel)" +%s')
+      reboot_time=$(remote.exec 'last reboot --time-format full | sed -n "s/wtmp begins //p"')
+      reboot_time=$(date -d"$reboot_time" +%s)
+      test "$reboot_time" -gt "$tree_birth"
+
+      # check that the component is in place
+      kern_ver=$(remote.exec uname -r)
+      comp_install_dir=/var/lib/snapd/kernel/pc-kernel/x1/lib/modules/"$kern_ver"/updates/"$NESTED_KERNEL_MODULES_COMP"
+      comp_dir=/snap/pc-kernel/components/mnt/"$NESTED_KERNEL_MODULES_COMP"/x1/modules/"$kern_ver"
+      test "$(remote.exec readlink -f "$comp_install_dir")" = "$comp_dir"
+
+      # module comes from a component
+      remote.exec modinfo -F filename efi_pstore | MATCH updates/"$NESTED_KERNEL_MODULES_COMP"/kmod/efi-pstore.ko
+      # module should have been loaded (pulled by systemd-pstore.service)
+      remote.exec lsmod | MATCH efi_pstore
+  }
+
+  # check component from store has been early-installed
+  check_efi_pstore
+
   if [ "${INSTALL_MODE}" != none ]; then
     # TODO: in a normal run, ubuntu-data-<someid> is used instead of
     # just "ubuntu-data". We need to figure out if this is OK.