Boot linux!

Author: object-Object

console.sh

@@ -1,16 +1,49 @@
 #!/bin/bash
 
+host=localhost
+port=5000
+device=uart0
+direction=both
+disconnectOnHalt=true
+sendRequest=true
+
+while [[ "$1" =~ ^- && ! "$1" == "--" ]]; do case $1 in
+    h | --host )
+        shift; host=$1
+        ;;
+    -p | --port )
+        shift; port=$1
+        ;;
+    -d | --device )
+        shift; device=$1
+        ;;
+    --no-disconnect )
+        shift; disconnectOnHalt=false
+        ;;
+    --no-request )
+        shift; sendRequest=false
+        ;;
+    *)
+        echo "Unknown option: $1"
+        exit 1
+esac; shift; done
+if [[ "$1" == '--' ]]; then shift; fi
+
 state=$(stty -g)
-if [[ "${DIRECTION:=both}" == "tx" ]]; then
+if [[ "$direction" == "tx" ]]; then
     stty raw opost
 else
     stty raw opost -echo
 fi
 
-{
-    echo "{\"type\": \"serial\", \"device\": \"${DEVICE:=uart0}\", \"overrun\": false, \"direction\": \"${DIRECTION}\", \"disconnectOnHalt\": ${DISCONNECT_ON_HALT:=true}}"
-    cat
-} | netcat -v "${HOST:=localhost}" "${PORT:=5000}"
+if [[ "$sendRequest" == "true" ]]; then
+    {
+        echo "{\"type\": \"serial\", \"device\": \"$device\", \"overrun\": false, \"direction\": \"$direction\", \"disconnectOnHalt\": $disconnectOnHalt}"
+        cat
+    } | netcat -v "$host" "$port"
+else
+    netcat -v "$host" "$port"
+fi
 
 stty "$state"
 

linux/Makefile

@@ -16,7 +16,7 @@ setup-buildroot:
 	curl --location "$(BUILDROOT_RELEASE)" | tar xzv --directory $(BUILDROOT)
 
 .PHONY: everything
-everything: load-configs dtbs all zsbl get-images
+everything: load-configs dtbs all opensbi-rebuild zsbl get-images
 
 .PHONY: dtbs-rebuild
 dtbs-rebuild: dtbs opensbi-rebuild zsbl get-images

linux/README.md

@@ -0,0 +1,21 @@
+# Linux
+
+## Debugging
+
+### objdump
+
+```
+riscv32-unknown-linux-gnu-objdump --disassembler-color=on --visualize-jumps=color --start-address=0xc00109ac --stop-address=0xc0010a2c --disassemble --source --line-numbers --show-all-symbols --wide output/build/vmlinux
+```
+
+### GDB
+
+- Start the terminal server:
+  ```sh
+  python -m mlogv32.scripts.terminal_server
+  ```
+- Connect gdb to the debug port:
+  ```sh
+  riscv32-unknown-linux-gnu-gdb output/build/vmlinux
+  tar rem host.docker.internal:5001
+  ```

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

@@ -7,23 +7,24 @@
     chassis-type = "embedded";
 
     chosen {
-        bootargs = "earlycon=sbi console=ttyS0";
+        // SBI: console=hvc
+        // UART0: console=ttyS0
+        // for debugging: kgdboc_earlycon=sbi kgdboc=ttyS0 kgdbwait
+        bootargs = "earlycon=sbi console=hvc";
         stdout-path = &uart0;
     };
 
     rom@0 {
         compatible = "mtd-rom";
         reg = <0x0 (16*1024*1024)>;
+        bank-width = <1>; // 8-bit "bus"
+
         #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;
         };
     };
@@ -78,37 +79,12 @@
         uart0: serial@f0000010 {
             compatible = "ns16550a";
             reg = <0xf0000010 0x20>;
-            clock-frequency = <10000000>;
-            reg-shift = <2>;
-            no-loopback-test = <1>;
-            fifo-size = <253>;
-        };
-
-        uart1: serial@f0000030 {
-            compatible = "ns16550a";
-            reg = <0xf0000030 0x20>;
-            clock-frequency = <10000000>;
-            reg-shift = <2>;
-            no-loopback-test = <1>;
-            fifo-size = <253>;
-        };
-
-        uart2: serial@f0000050 {
-            compatible = "ns16550a";
-            reg = <0xf0000050 0x20>;
-            clock-frequency = <10000000>;
-            reg-shift = <2>;
-            no-loopback-test = <1>;
-            fifo-size = <253>;
-        };
-
-        uart3: serial@f0000070 {
-            compatible = "ns16550a";
-            reg = <0xf0000070 0x20>;
-            clock-frequency = <10000000>;
             reg-shift = <2>;
-            no-loopback-test = <1>;
+            interrupts-extended = <&intc 9>;
+            clock-frequency = <(38400*16)>;
             fifo-size = <253>;
+            no-loopback-test;
+            // TODO: https://github.com/torvalds/linux/blob/8c2e52ebbe885c7eeaabd3b7ddcdc1246fc400d2/drivers/tty/serial/8250/8250_of.c#L233
         };
 
         syscon: syscon@fffffff0 {

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

@@ -1,4 +1,5 @@
 CONFIG_NO_HZ_IDLE=y
+CONFIG_KALLSYMS_ALL=y
 CONFIG_NONPORTABLE=y
 CONFIG_ARCH_RV32I=y
 # CONFIG_RISCV_ISA_C is not set
@@ -26,14 +27,20 @@ CONFIG_JUMP_LABEL=y
 CONFIG_DEVTMPFS=y
 CONFIG_DEVTMPFS_MOUNT=y
 CONFIG_MTD=y
+CONFIG_MTD_BLOCK_RO=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_VT_HW_CONSOLE_BINDING=y
 CONFIG_SERIAL_8250=y
+# CONFIG_SERIAL_8250_DEPRECATED_OPTIONS is not set
+# CONFIG_SERIAL_8250_16550A_VARIANTS is not set
 CONFIG_SERIAL_8250_CONSOLE=y
+CONFIG_SERIAL_OF_PLATFORM=y
 CONFIG_SERIAL_EARLYCON_RISCV_SBI=y
+CONFIG_HVC_RISCV_SBI=y
 # CONFIG_HW_RANDOM is not set
 CONFIG_POWER_RESET=y
 CONFIG_POWER_RESET_SYSCON=y
@@ -46,7 +53,15 @@ CONFIG_DUMMY_CONSOLE_ROWS=38
 # CONFIG_VIRTIO_MENU is not set
 # CONFIG_VHOST_MENU is not set
 # CONFIG_NVMEM is not set
+CONFIG_OVERLAY_FS=y
+CONFIG_TMPFS=y
 CONFIG_CRAMFS=y
 CONFIG_CRAMFS_MTD=y
 CONFIG_PRINTK_TIME=y
+CONFIG_DEBUG_KERNEL=y
+# CONFIG_DEBUG_MISC is not set
+CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y
+CONFIG_GDB_SCRIPTS=y
 CONFIG_FRAME_WARN=2048
+CONFIG_KGDB=y
+# CONFIG_FTRACE is not set

linux/buildroot/board/mlogv32/linux.config

@@ -0,0 +1,39 @@
+From 6dd1871b195d17d3ea2121cc030663c76da309e1 Mon Sep 17 00:00:00 2001
+From: object-Object <[email protected]>
+Date: Wed, 9 Jul 2025 16:50:43 -0400
+Subject: [PATCH 1/2] Add sbi_debug_console_read support to SBI earlycon
+
+---
+ drivers/tty/serial/earlycon-riscv-sbi.c | 11 +++++++++--
+ 1 file changed, 9 insertions(+), 2 deletions(-)
+
+diff --git a/drivers/tty/serial/earlycon-riscv-sbi.c b/drivers/tty/serial/earlycon-riscv-sbi.c
+index 0162155f0c83..a526974c5416 100644
+--- a/drivers/tty/serial/earlycon-riscv-sbi.c
++++ b/drivers/tty/serial/earlycon-riscv-sbi.c
+@@ -37,12 +37,19 @@ static void sbi_dbcn_console_write(struct console *con,
+ 	}
+ }
+
++static int sbi_dbcn_console_read(struct console *con,
++				 char *s, unsigned int n)
++{
++	return sbi_debug_console_read(s, n);
++}
++
+ static int __init early_sbi_setup(struct earlycon_device *device,
+ 				  const char *opt)
+ {
+-	if (sbi_debug_console_available)
++	if (sbi_debug_console_available) {
+ 		device->con->write = sbi_dbcn_console_write;
+-	else if (IS_ENABLED(CONFIG_RISCV_SBI_V01))
++		device->con->read = sbi_dbcn_console_read;
++	} else if (IS_ENABLED(CONFIG_RISCV_SBI_V01))
+ 		device->con->write = sbi_0_1_console_write;
+ 	else
+ 		return -ENODEV;
+
+base-commit: 19272b37aa4f83ca52bdf9c16d5d81bdd1354494
+--
+2.25.1

linux/buildroot/patches/linux/0001-Add-sbi_debug_console_read-support-to-SBI-earlycon.patch

@@ -0,0 +1,28 @@
+From 3d22caf2bee6f6ff4b9ce1c53a3bc046cfcd14e4 Mon Sep 17 00:00:00 2001
+From: object-Object <[email protected]>
+Date: Fri, 11 Jul 2025 16:43:41 -0400
+Subject: [PATCH 2/2] Hack: remove contents of flush_icache_pte
+
+---
+ arch/riscv/mm/cacheflush.c | 6 ------
+ 1 file changed, 6 deletions(-)
+
+diff --git a/arch/riscv/mm/cacheflush.c b/arch/riscv/mm/cacheflush.c
+index 4ca5aafce22e..667ab1659bb9 100644
+--- a/arch/riscv/mm/cacheflush.c
++++ b/arch/riscv/mm/cacheflush.c
+@@ -99,12 +99,6 @@ void flush_icache_mm(struct mm_struct *mm, bool local)
+ #ifdef CONFIG_MMU
+ void flush_icache_pte(struct mm_struct *mm, pte_t pte)
+ {
+-	struct folio *folio = page_folio(pte_page(pte));
+-
+-	if (!test_bit(PG_dcache_clean, &folio->flags)) {
+-		flush_icache_mm(mm, false);
+-		set_bit(PG_dcache_clean, &folio->flags);
+-	}
+ }
+ #endif /* CONFIG_MMU */
+
+--
+2.25.1

linux/buildroot/patches/linux/0002-Hack-remove-contents-of-flush_icache_pte.patch

@@ -76,6 +76,25 @@ def status(self):
         self._send_request(StatusRequest())
         return self._recv_response(StatusResponse)
 
+    def serial(
+        self,
+        device: UartDevice,
+        *,
+        overrun: bool = False,
+        stop_on_halt: bool = False,
+        disconnect_on_halt: bool = False,
+    ):
+        self._send_request(
+            SerialRequest(
+                device=device,
+                overrun=overrun,
+                direction="both",
+                stopOnHalt=stop_on_halt,
+                disconnectOnHalt=disconnect_on_halt,
+            )
+        )
+        return self.socket
+
     def _send_request(self, request: Request) -> None:
         message = request.model_dump_json() + "\n"
         logger.log(self.log_level, f"Sending request: {message.rstrip()}")
@@ -144,14 +163,30 @@ class StatusRequest(BaseModel):
     type: Literal["status"] = "status"
 
 
+type UartDevice = Literal["uart0", "uart1", "uart2", "uart3"]
+
+
+type UartDirection = Literal["both", "rx", "tx"]
+
+
+class SerialRequest(BaseModel):
+    type: Literal["serial"] = "serial"
+    device: UartDevice
+    overrun: bool
+    direction: UartDirection
+    stopOnHalt: bool
+    disconnectOnHalt: bool
+
+
 type Request = Annotated[
     FlashRequest
     | DumpRequest
     | StartRequest
     | WaitRequest
     | UnpauseRequest
     | StopRequest
-    | StatusRequest,
+    | StatusRequest
+    | SerialRequest,
     Field(discriminator="type"),
 ]