dde_linux: add virt_linux lx_emul flavor

To support device-less protocol-stacks only ports, we can use a
Virt I/O Linux kernel flavor, and export the lx_kit/lx_emul parts
not depending on platform API and devices.

Ref #4397

repos/dde_linux/lib/import/import-lx_emul.mk

@@ -0,0 +1,12 @@
+LIBS += virt_linux_generated
+
+LX_SRC_DIR := $(call select_from_ports,linux)/src/linux
+ifeq ($(wildcard $(LX_SRC_DIR)),)
+LX_SRC_DIR := $(call select_from_repositories,src/linux)
+endif
+
+LX_GEN_DIR := $(LIB_CACHE_DIR)/virt_linux_generated
+
+-include $(call select_from_repositories,lib/import/import-lx_emul_common.inc)
+
+SRC_CC  += lx_kit/memory_non_dma.cc

repos/dde_linux/lib/mk/lx_emul.mk

@@ -0,0 +1,2 @@
+# the lx_emul libray exists only for the import file
+

repos/dde_linux/lib/mk/spec/x86_64/virt_linux_generated.mk

@@ -0,0 +1,3 @@
+LINUX_ARCH=x86_64
+
+include $(REP_DIR)/lib/mk/virt_linux_generated.inc

repos/dde_linux/lib/mk/virt_linux_generated.inc

@@ -0,0 +1,30 @@
+CUSTOM_TARGET_DEPS := kernel_build.phony
+
+LX_DIR := $(call select_from_ports,linux)/src/linux
+PWD    := $(shell pwd)
+
+LX_MK_ARGS = ARCH=$(LINUX_ARCH) CROSS_COMPILE=$(CROSS_DEV_PREFIX)
+
+#
+# Linux kernel configuration
+#
+
+# define 'LX_ENABLE' and 'LX_DISABLE'
+include $(REP_DIR)/src/virt_linux/target.inc
+
+# filter for make output of kernel build system
+BUILD_OUTPUT_FILTER = 2>&1 | sed "s/^/      [Linux]  /"
+
+kernel_config.tag:
+	$(MSG_CONFIG)Linux
+	$(VERBOSE)$(MAKE) -C $(LX_DIR) O=$(PWD) $(LX_MK_ARGS) tinyconfig $(BUILD_OUTPUT_FILTER)
+	$(VERBOSE)$(LX_DIR)/scripts/config $(addprefix --enable ,$(LX_ENABLE))
+	$(VERBOSE)$(LX_DIR)/scripts/config $(addprefix --disable ,$(LX_DISABLE))
+	$(VERBOSE)$(MAKE) $(LX_MK_ARGS) olddefconfig $(BUILD_OUTPUT_FILTER)
+	$(VERBOSE)$(MAKE) $(LX_MK_ARGS) prepare      $(BUILD_OUTPUT_FILTER)
+	$(VERBOSE)touch $@
+
+# update Linux kernel config on makefile changes
+kernel_config.tag: $(MAKEFILE_LIST)
+
+kernel_build.phony: kernel_config.tag

repos/dde_linux/src/virt_linux/README

@@ -0,0 +1,14 @@
+
+# RUN virt_linux under Qemu (x86_64)
+
+qemu-system-x86_64 \
+  -no-kvm -m 512 \
+  -chardev stdio,id=virtiocon0 \
+  -device virtio-serial \
+  -device virtconsole,chardev=virtiocon0 \
+  -netdev tap,id=net0,ifname=tap0,script=no,downscript=no \
+  -net nic,model=virtio,netdev=net0 \
+  -kernel virt_linux/x86_64/arch/x86_64/boot/bzImage \
+  -initrd busybox/initramfs.cpio.gz \
+  -append "console=hvc0 ip=dhcp"
+

repos/dde_linux/src/virt_linux/target.inc

@@ -0,0 +1,35 @@
+#
+# Linux kernel configuration
+#
+
+# kernel fundamentals
+LX_ENABLE += TTY SERIAL_EARLYCON SERIAL_OF_PLATFORM PRINTK HAS_IOMEM
+
+# initrd support
+LX_ENABLE += BINFMT_ELF BLK_DEV_INITRD
+
+# network infrastructure
+LX_ENABLE += NET NETDEVICES
+
+# PCI support
+LX_ENABLE += PCI
+
+# Virtio devices
+LX_ENABLE += VIRTIO_MENU VIRTIO_PCI VIRTIO_NET VIRTIO_CONSOLE
+
+# network protocols
+LX_ENABLE += INET IP_PNP IP_PNP_DHCP
+
+# random number generator
+LX_ENABLE += HW_RANDOM ARCH_RANDOM RANDOM_TRUST_CPU RANDOM_TRUST_BOOTLOADER
+LX_ENABLE += CRYPTO_JITTERENTROPY CRYPTO_ANSI_CPRNG HW_RANDOM_TIMERIOMEM
+
+# wireguard driver
+LX_ENABLE += WIREGUARD WIREGUARD_DEBUG
+
+# disable optimization not possible in PIC code under Genode
+LX_DISABLE += CC_HAS_ASM_GOTO
+
+# slim down kernel by removing superfluous drivers
+LX_DISABLE += HID HID_GENERIC USB_HID VGA_CONSOLE DUMMY_CONSOLE NLS VGA_ARB DEBUG_LIST
+LX_DISABLE += INPUT_KEYBOARD INPUT_MOUSE WLAN WIRELESS ETHERNET

repos/dde_linux/src/virt_linux/x86_32/target.mk

@@ -0,0 +1,37 @@
+TARGET   := x86_32_virt_linux
+REQUIRES := x86_32
+
+CUSTOM_TARGET_DEPS := kernel_build.phony
+
+LX_DIR := $(call select_from_ports,linux)/src/linux
+PWD    := $(shell pwd)
+
+LX_MK_ARGS = ARCH=x86 CROSS_COMPILE=$(CROSS_DEV_PREFIX)
+
+#
+# Linux kernel configuration
+#
+# Start with 'make tinyconfig', enable/disable options via 'scripts/config',
+# and resolve config dependencies via 'make olddefconfig'.
+#
+
+# define 'LX_ENABLE' and 'LX_DISABLE'
+include $(REP_DIR)/src/virt_linux/target.inc
+
+# filter for make output of kernel build system
+BUILD_OUTPUT_FILTER = 2>&1 | sed "s/^/      [Linux]  /"
+
+kernel_config.tag:
+	$(MSG_CONFIG)Linux
+	$(VERBOSE)$(MAKE) -C $(LX_DIR) O=$(PWD) $(LX_MK_ARGS) tinyconfig $(BUILD_OUTPUT_FILTER)
+	$(VERBOSE)$(LX_DIR)/scripts/config --file $(PWD)/.config $(addprefix --enable ,$(LX_ENABLE))
+	$(VERBOSE)$(LX_DIR)/scripts/config --file $(PWD)/.config $(addprefix --disable ,$(LX_DISABLE))
+	$(VERBOSE)$(MAKE) $(LX_MK_ARGS) olddefconfig $(BUILD_OUTPUT_FILTER)
+	$(VERBOSE)touch $@
+
+# update Linux kernel config on makefile changes
+kernel_config.tag: $(MAKEFILE_LIST)
+
+kernel_build.phony: kernel_config.tag
+	$(MSG_BUILD)Linux
+	$(VERBOSE)$(MAKE) $(LX_MK_ARGS) bzImage $(BUILD_OUTPUT_FILTER)

repos/dde_linux/src/virt_linux/x86_64/target.mk

@@ -0,0 +1,37 @@
+TARGET   := x86_64_virt_linux
+REQUIRES := x86_64
+
+CUSTOM_TARGET_DEPS := kernel_build.phony
+
+LX_DIR := $(call select_from_ports,linux)/src/linux
+PWD    := $(shell pwd)
+
+LX_MK_ARGS = ARCH=x86_64 CROSS_COMPILE=$(CROSS_DEV_PREFIX)
+
+#
+# Linux kernel configuration
+#
+# Start with 'make tinyconfig', enable/disable options via 'scripts/config',
+# and resolve config dependencies via 'make olddefconfig'.
+#
+
+# define 'LX_ENABLE' and 'LX_DISABLE'
+include $(REP_DIR)/src/virt_linux/target.inc
+
+# filter for make output of kernel build system
+BUILD_OUTPUT_FILTER = 2>&1 | sed "s/^/      [Linux]  /"
+
+kernel_config.tag:
+	$(MSG_CONFIG)Linux
+	$(VERBOSE)$(MAKE) -C $(LX_DIR) O=$(PWD) $(LX_MK_ARGS) tinyconfig $(BUILD_OUTPUT_FILTER)
+	$(VERBOSE)$(LX_DIR)/scripts/config --file $(PWD)/.config $(addprefix --enable ,$(LX_ENABLE))
+	$(VERBOSE)$(LX_DIR)/scripts/config --file $(PWD)/.config $(addprefix --disable ,$(LX_DISABLE))
+	$(VERBOSE)$(MAKE) $(LX_MK_ARGS) olddefconfig $(BUILD_OUTPUT_FILTER)
+	$(VERBOSE)touch $@
+
+# update Linux kernel config on makefile changes
+kernel_config.tag: $(MAKEFILE_LIST)
+
+kernel_build.phony: kernel_config.tag
+	$(MSG_BUILD)Linux
+	$(VERBOSE)$(MAKE) $(LX_MK_ARGS) bzImage $(BUILD_OUTPUT_FILTER)