Disable XIP, use cramfs, other kernel changes

Author: object-Object

.github/.devcontainer/Dockerfile

@@ -41,7 +41,7 @@ RUN SNIPPET="export PROMPT_COMMAND='history -a' && export HISTFILE=/commandhisto
 
 # buildroot dependencies
 RUN apt-get update \
-    && apt-get install -y --no-install-recommends cpio bc \
+    && apt-get install -y --no-install-recommends cpio bc device-tree-compiler \
     && rm -rf /var/lib/apt/lists/*
 
 # avoid permission issues with cargo if cargo install runs as root

.vscode/settings.json

@@ -25,5 +25,9 @@
     "python.analysis.diagnosticMode": "workspace",
     "python.analysis.packageIndexDepths": [{ "name": "jinja2", "depth": 2 }],
     "files.eol": "\n",
-    "yaml.customTags": ["tag:yaml.org,2002:python/object/apply:builtins.range sequence"]
+    "yaml.customTags": [
+        "tag:yaml.org,2002:python/object/apply:builtins.range sequence",
+        "tag:yaml.org,2002:python/object/apply:builtins.sum sequence"
+    ],
+    "git.detectSubmodules": false
 }

linux/Makefile

@@ -1,6 +1,3 @@
-MAKEFLAGS += --no-builtin-rules
-.SUFFIXES:
-
 THIS_DIR := $(abspath $(dir $(lastword $(MAKEFILE_LIST))))
 
 BR2_EXTERNAL_SRC := $(THIS_DIR)/buildroot
@@ -18,18 +15,44 @@ MAKE_BUILDROOT = $(MAKE) -C $(BUILDROOT) BR2_EXTERNAL=$(BR2_EXTERNAL)
 setup-buildroot:
 	curl --location "$(BUILDROOT_RELEASE)" | tar xzv --directory $(BUILDROOT)
 
+.PHONY: everything
+everything: load-configs dtbs all zsbl get-images
+
+.PHONY: dtbs-rebuild
+dtbs-rebuild: dtbs opensbi-rebuild zsbl get-images
+
+.PHONY: load-configs
+load-configs: mlogv32_defconfig
+
 .PHONY: get-images
 get-images:
 	rm -rf $(THIS_DIR)/output
 
 	mkdir -p $(THIS_DIR)/output/images
 	cp -r $(BUILDROOT)/output/images $(THIS_DIR)/output
-	-riscv32-unknown-linux-gnu-objdump -d $(THIS_DIR)/output/images/fw_jump.elf > $(THIS_DIR)/output/images/fw_jump.dump
-	-riscv32-unknown-linux-gnu-objdump -d $(THIS_DIR)/output/images/zsbl.elf > $(THIS_DIR)/output/images/zsbl.dump
 
 	mkdir -p $(THIS_DIR)/output/build
 	cp $(BUILDROOT)/output/build/linux-*/vmlinux $(THIS_DIR)/output/build
-	-riscv32-unknown-linux-gnu-objdump -d $(THIS_DIR)/output/build/vmlinux > $(THIS_DIR)/output/build/vmlinux.dump
+
+.PHONY: dump-images
+dump-images:
+	-riscv32-unknown-linux-gnu-objdump \
+		--wide \
+		--disassemble \
+		$(THIS_DIR)/output/images/fw_jump.elf > $(THIS_DIR)/output/images/fw_jump.dump
+
+	-riscv32-unknown-linux-gnu-objdump \
+		--wide \
+		--disassemble \
+		--show-all-symbols \
+		--section .text \
+		--section .loader \
+		$(THIS_DIR)/output/images/zsbl.elf > $(THIS_DIR)/output/images/zsbl.dump
+
+	-riscv32-unknown-linux-gnu-objdump \
+		--wide \
+		--disassemble \
+		$(THIS_DIR)/output/build/vmlinux > $(THIS_DIR)/output/build/vmlinux.dump
 
 # copy this directory to/from BR2_EXTERNAL to make buildroot run faster when this directory is in a Windows Docker volume
 %:
@@ -38,5 +61,5 @@ ifeq ($(BR2_EXTERNAL_SRC),$(BR2_EXTERNAL))
 else
 	rsync --archive --delete $(BR2_EXTERNAL_SRC)/ $(BR2_EXTERNAL)
 	-$(MAKE_BUILDROOT) $@
-	cp -r --no-target-directory $(BR2_EXTERNAL) $(BR2_EXTERNAL_SRC)
+	cp -r --update --no-target-directory $(BR2_EXTERNAL) $(BR2_EXTERNAL_SRC)
 endif

linux/buildroot/board/mlogv32/dts/mlogv32.dtb

@@ -11,9 +11,27 @@
         stdout-path = &uart0;
     };
 
+    rom@0 {
+        compatible = "mtd-rom";
+        reg = <0x0 (16*1024*1024)>;
+        #address-cells = <1>;
+        #size-cells = <1>;
+        bank-width = <1>; // 8-bit "bus"
+
+        // align rootfs to pgdir boundary
+        rootfs@1000 {
+            label = "rootfs";
+            reg = <0x1000 (16*1024*1024 - 0x1000)>;
+            bank-width = <1>;
+            read-only;
+            linux,rootfs;
+        };
+    };
+
     memory@80000000 {
         device_type = "memory";
-        reg = <0x80000000 (16 * 1024*1024 - 256 * 1024)>;
+        // the last 256K are reserved for OpenSBI
+        reg = <0x80000000 (16*1024*1024 - 256*1024)>;
     };
 
     cpus {
@@ -25,13 +43,32 @@
             device_type = "cpu";
             compatible = "riscv";
             mmu-type = "riscv,sv32";
-            reg = <0>;
-            riscv,isa = "rv32ima";
+            reg = <0>; // hart id
             riscv,isa-base = "rv32i";
-            riscv,isa-extensions = "i", "m", "a", "zicntr", "zicsr", "zifencei";
+            riscv,isa-extensions =
+                "i",
+                "m",
+                "a",
+                "zicntr",
+                "zicsr",
+                "zifencei",
+                "zihintpause",
+                "sstc",
+                "svade";
+
+            intc: interrupt-controller {
+                compatible = "riscv,cpu-intc";
+                #interrupt-cells = <1>;
+                interrupt-controller;
+            };
         };
     };
 
+    timer {
+        compatible = "riscv,timer";
+        interrupts-extended = <&intc 5>;
+    };
+
     soc {
         #address-cells = <1>;
         #size-cells = <1>;

linux/buildroot/board/mlogv32/dts/mlogv32.dts

@@ -1,20 +1,35 @@
-CONFIG_BLK_DEV_INITRD=y
-CONFIG_INITRAMFS_SOURCE="${BR_BINARIES_DIR}/rootfs.cpio"
+CONFIG_NO_HZ_IDLE=y
 CONFIG_NONPORTABLE=y
 CONFIG_ARCH_RV32I=y
 # CONFIG_RISCV_ISA_C is not set
+# CONFIG_RISCV_ISA_ZAWRS is not set
+# CONFIG_RISCV_ISA_ZABHA is not set
+# CONFIG_RISCV_ISA_ZACAS is not set
 # CONFIG_RISCV_ISA_ZBA is not set
+# CONFIG_RISCV_ISA_ZBB is not set
+# CONFIG_RISCV_ISA_ZBC is not set
+# CONFIG_RISCV_ISA_ZBKB is not set
+# CONFIG_RISCV_ISA_ZICBOM is not set
+# CONFIG_RISCV_ISA_ZICBOZ is not set
 # CONFIG_FPU is not set
 CONFIG_RISCV_EMULATED_UNALIGNED_ACCESS=y
 CONFIG_HZ_100=y
-CONFIG_XIP_KERNEL=y
-CONFIG_XIP_PHYS_ADDR=0x400000
-CONFIG_BUILTIN_DTB=y
-CONFIG_BUILTIN_DTB_NAME="mlogv32"
+# CONFIG_EFI is not set
+CONFIG_PHYS_RAM_BASE_FIXED=y
+# CONFIG_RISCV_ISA_FALLBACK is not set
+# CONFIG_SUSPEND is not set
+CONFIG_JUMP_LABEL=y
+# CONFIG_STRICT_KERNEL_RWX is not set
 # CONFIG_GCC_PLUGINS is not set
-CONFIG_SPARSEMEM_MANUAL=y
+# CONFIG_MQ_IOSCHED_DEADLINE is not set
+# CONFIG_MQ_IOSCHED_KYBER is not set
 CONFIG_DEVTMPFS=y
 CONFIG_DEVTMPFS_MOUNT=y
+CONFIG_MTD=y
+CONFIG_MTD_ROM=y
+CONFIG_MTD_PHYSMAP=y
+CONFIG_MTD_PHYSMAP_OF=y
+CONFIG_BLK_DEV_RAM=y
 # CONFIG_INPUT_MOUSE is not set
 CONFIG_SERIAL_8250=y
 CONFIG_SERIAL_8250_CONSOLE=y
@@ -23,21 +38,15 @@ CONFIG_SERIAL_EARLYCON_RISCV_SBI=y
 CONFIG_POWER_RESET=y
 CONFIG_POWER_RESET_SYSCON=y
 CONFIG_POWER_RESET_SYSCON_POWEROFF=y
+# CONFIG_HWMON is not set
 CONFIG_DUMMY_CONSOLE_COLUMNS=70
 CONFIG_DUMMY_CONSOLE_ROWS=38
 # CONFIG_HID_SUPPORT is not set
 # CONFIG_USB_SUPPORT is not set
-CONFIG_ROMFS_FS=y
-CONFIG_PRINTK_CALLER=y
-CONFIG_DEBUG_KERNEL=y
-CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y
-CONFIG_DEBUG_INFO_REDUCED=y
+# CONFIG_VIRTIO_MENU is not set
+# CONFIG_VHOST_MENU is not set
+# CONFIG_NVMEM is not set
+CONFIG_CRAMFS=y
+CONFIG_CRAMFS_MTD=y
+CONFIG_PRINTK_TIME=y
 CONFIG_FRAME_WARN=2048
-CONFIG_READABLE_ASM=y
-CONFIG_DEBUG_PAGEALLOC=y
-CONFIG_DEBUG_OBJECTS=y
-CONFIG_DEBUG_VM=y
-CONFIG_DEBUG_VIRTUAL=y
-CONFIG_PANIC_ON_OOPS=y
-CONFIG_DEBUG_KOBJECT=y
-# CONFIG_FTRACE is not set

linux/buildroot/board/mlogv32/linux.config

@@ -1,38 +1,85 @@
-.section .text.start
-.global _start
-_start:
-    // initialize icache
-    la t0, _etext
-    .insn i CUSTOM_0, 0, zero, t0, 0
-
-    // copy payload to RAM
-    la t0, _sipayload
-    la t1, _spayload
-    la t2, _epayload
+.set UART0_BASE, 0xf0000010
+
+.macro log message
+    la a0, 1f
+    call do_print
+.pushsection .rodata
+1:  .asciz "[zsbl] \message\r\n"
+.popsection
+.endm
+
+.macro copy name
+    la t0, _si\name
+    la t1, _s\name
+    la t2, _e\name
 1:
     lw t3, 0(t0)
     sw t3, 0(t1)
     addi t0, t0, 4
     addi t1, t1, 4
     bltu t1, t2, 1b
+.endm
+
+.section .text
+.global _start
+_start:
+    // enable UART
+    la t0, UART0_BASE
+    li t1, 1
+    sb t1, 8(t0)
 
-    // hartid
-    li a0, 0
+    // copy loader to RAM
+    log "loading kernel..."
+    copy loader
 
-    // DTB
-    li a1, 0
+    // copy kernel to RAM
+    call loader
+
+    // copy OpenSBI to RAM
+    log "loading OpenSBI..."
+    copy opensbi
+
+    log "done!"
+
+    // wait for UART THR to drain so we don't lose any logs if OpenSBI initializes UART0 in the same tick
+    la t0, UART0_BASE
+1:
+    lbu t1, 0x14(t0)
+    andi t1, t1, 0b100000
+    beqz t1, 1b
+
+    // jump to OpenSBI
+    li a0, 0 // hartid
+    li a1, 0 // DTB (null)
+    tail _sopensbi
+
+do_print:
+    la t0, UART0_BASE
+1:
+    lbu t1, 0(a0)
+    beqz t1, 2f
+    sb t1, 0(t0)
+    addi a0, a0, 1
+    j 1b
+2:
+    ret
 
-    // jump to payload
-    call _spayload
+.section .loader, "ax", @progbits
+.balign 4
+loader:
+    // copy kernel to RAM
+    // we do this here so the copy operation can be covered by the icache
+    copy kernel
+    ret
 
-    // if the payload returns, halt the processor
-    li t0, 0xfffffff0
-    sw zero, 0(t0)
+.section .rootfs, "a", @progbits
+.balign 4
+    .incbin ZSBL_ROOTFS_PATH
 
-.section .data.payload
-.align 4
-.incbin ZSBL_PAYLOAD_PATH
+.section .kernel, "ax", @progbits
+.balign 4
+    .incbin ZSBL_KERNEL_PATH
 
-.section .rodata.kernel
-.align 4
-.incbin ZSBL_KERNEL_PATH
+.section .opensbi, "ax", @progbits
+.balign 4
+    .incbin ZSBL_OPENSBI_PATH