Prerequisite changes to switch to 6.1 kernel

- Add new partitions "system_dlkm" and "vendor_dlkm"
    - These are added to the fstab to ensure they're mounted.
    - These new partitions contain the remainder of the kernel modules
      that are loaded at second stage init. The initial kernel modules
      that are required to boot are contained in the vendor ramdisk.
- Set mac80211_hwsim.radios=0 kernel module parameter
    - Cuttlefish uses bootconfig to set kernel parameters at
      build time. This requires support in the bootloader, but
      not all hypervisors support bootloaders. In this case we set the kernel
      module's parameter on the kernel command line.

Bug: 315309338
Test: Build and verify functionality manually on a board
Change-Id: Ia5c1fb6cc584833ff849f3759f68ea8872cb7033

2 files changed, 43 insertions, 15 deletions

diff --git a/product_files/fstab.trout b/product_files/fstab.trout
index 82726c8..d7c98c0 100644
--- a/product_files/fstab.trout
+++ b/product_files/fstab.trout
@@ -10,6 +10,8 @@ odm /odm ext4 noatime,ro,errors=panic wait,logical,first_stage_mount,slotselect,
 product /product ext4 noatime,ro,errors=panic wait,logical,first_stage_mount,slotselect,avb
 system_ext /system_ext ext4 noatime,ro,errors=panic wait,logical,first_stage_mount,slotselect,avb=vbmeta_system
 vendor /vendor ext4 noatime,ro,errors=panic wait,logical,first_stage_mount,slotselect,avb=vbmeta
+vendor_dlkm /vendor_dlkm ext4 noatime,ro,errors=panic wait,logical,first_stage_mount,slotselect,avb=vbmeta_dlkm
+system_dlkm /system_dlkm ext4 noatime,ro,errors=panic wait,logical,first_stage_mount,slotselect,avb=vbmeta_system_dlkm
 /dev/block/zram0 none swap defaults zramsize=75%
 /tmp /sdcard none defaults,bind recoveryonly
 /devices/*/block/vdb auto auto defaults voldmanaged=sdcard1:auto,encryptable=userdata
diff --git a/trout_arm64/BoardConfig.mk b/trout_arm64/BoardConfig.mk
index 3d20522..f99db1a 100644
--- a/trout_arm64/BoardConfig.mk
+++ b/trout_arm64/BoardConfig.mk
@@ -51,32 +51,55 @@ BOARD_BOOT_HEADER_VERSION := 4
 # Kernel - prefer version 5.10 by default for trout
 TARGET_KERNEL_USE ?= 5.10
 
+# Select the prebuilt trout kernel if 5.10 or 5.4 is in use
 TROUT_KERNEL_DIR ?= $(wildcard device/google/trout-kernel/$(TARGET_KERNEL_USE)-arm64)
 
-# The trout kernel is provided as source to AOSP,
-# and thus we cannot rely on it existing outside of Google-internal builds. Make sure not to try
-# and include a missing kernel image.
-ifndef TARGET_KERNEL_PATH
-# wildcard is for existence checking,
-# so TROUT_KERNEL_IMAGE is suppose to be a list that contains at most one path.
-# The foreach below is only for extracting the path from the list.
-TROUT_KERNEL_IMAGE := $(wildcard $(TROUT_KERNEL_DIR)/Image)
-$(foreach kernel_img, $(TROUT_KERNEL_IMAGE), $(eval TARGET_KERNEL_PATH := $(kernel_img)))
-endif
-
 TARGET_BOARD_PLATFORM := vsoc_arm64
 TARGET_ARCH := arm64
 TARGET_ARCH_VARIANT := armv8-a
 TARGET_CPU_ABI := arm64-v8a
 TARGET_CPU_VARIANT := cortex-a53
 
--include device/google/trout/shared/BoardConfig.mk
+ifneq ($(TROUT_KERNEL_DIR),)
+KERNEL_MODULES_PATH ?= $(TROUT_KERNEL_DIR)
+TARGET_KERNEL_PATH ?= $(TROUT_KERNEL_DIR)/Image
 
-TROUT_KO_DIR ?= $(TROUT_KERNEL_DIR)
-ifneq ($(TROUT_KO_DIR),)
-BOARD_VENDOR_RAMDISK_KERNEL_MODULES := $(wildcard $(TROUT_KO_DIR)/*.ko)
+# For local builds of the android12-5.10 kernel, this directory doesn't exist.
+# The system_dlkm partition won't have any kernel modules in it, which matches
+# how this kernel was originally used.
+#
+# For prebuilts of the android12-5.10 kernel, the result is the same.
+#
+# For local builds of the android14-6.1 kernel and later, this directory should
+# be created by extracting the system_dlkm_staging_archive.tar.gz file in the
+# build directory of the kernel before building the android image.
+#
+# For prebuilts of the android14-6.1 kernel and later, TROUT_KERNEL_DIR should
+# not be specified, in which case it will follow whatever the upstream
+# cuttlefish device specifies.
+SYSTEM_DLKM_SRC ?= $(TROUT_KERNEL_DIR)/flatten/lib/modules
 endif
 
+# The list of modules strictly/only required either to reach second stage
+# init, OR for recovery. Do not use this list to workaround second stage
+# issues.
+RAMDISK_KERNEL_MODULES ?= \
+    failover.ko \
+    nd_virtio.ko \
+    net_failover.ko \
+    virtio_blk.ko \
+    virtio_console.ko \
+    virtio_dma_buf.ko \
+    virtio-gpu.ko \
+    virtio_input.ko \
+    virtio_net.ko \
+    virtio_mmio.ko \
+    virtio_pci.ko \
+    virtio-rng.ko \
+    vmw_vsock_virtio_transport.ko \
+
+-include device/google/trout/shared/BoardConfig.mk
+
 AUDIOSERVER_MULTILIB := first
 
 HOST_CROSS_OS := linux_bionic
@@ -110,3 +133,6 @@ BOARD_KERNEL_CMDLINE += androidboot.wifi_mac_prefix=5554
 
 # Add default fstab settings
 BOARD_KERNEL_CMDLINE += androidboot.fstab_name=fstab androidboot.fstab_suffix=trout
+
+# Prevent mac80211_hwsim from simulating any radios
+BOARD_KERNEL_CMDLINE += mac80211_hwsim.radios=0