[Modified] change toolchain to la32r

.gitmodules

@@ -7,3 +7,6 @@
 [submodule "lasoft/la32r-nemu"]
 	path = lasoft/la32r-nemu
 	url = https://gitee.com/wwt_panache/la32r-nemu
+[submodule "la32r-toolchains"]
+	path = la32r-toolchains
+	url = https://gitee.com/loongson-edu/la32r-toolchains

lasoft/xv6-la/Makefile

@@ -32,23 +32,7 @@ OBJS = \
 
 # riscv64-unknown-elf- or riscv64-linux-gnu-
 # perhaps in /opt/riscv/bin
-#TOOLPREFIX = 
+TOOLPREFIX ?= 
-
-# Try to infer the correct TOOLPREFIX if not set
-ifndef TOOLPREFIX
-TOOLPREFIX := $(shell if riscv64-unknown-elf-objdump -i 2>&1 | grep 'elf64-big' >/dev/null 2>&1; \
-	then echo 'riscv64-unknown-elf-'; \
-	elif riscv64-linux-gnu-objdump -i 2>&1 | grep 'elf64-big' >/dev/null 2>&1; \
-	then echo 'riscv64-linux-gnu-'; \
-	elif riscv64-unknown-linux-gnu-objdump -i 2>&1 | grep 'elf64-big' >/dev/null 2>&1; \
-	then echo 'riscv64-unknown-linux-gnu-'; \
-	else echo "***" 1>&2; \
-	echo "*** Error: Couldn't find a riscv64 version of GCC/binutils." 1>&2; \
-	echo "*** To turn off this error, run 'gmake TOOLPREFIX= ...'." 1>&2; \
-	echo "***" 1>&2; exit 1; fi)
-endif
-
-QEMU = qemu-system-riscv64
 
 CC = $(TOOLPREFIX)gcc
 AS = $(TOOLPREFIX)gas
@@ -146,30 +130,5 @@ clean:
         $U/usys.S \
 	$(UPROGS)
 
-# try to generate a unique GDB port
-GDBPORT = $(shell expr `id -u` % 5000 + 25000)
-# QEMU's gdb stub command line changed in 0.11
-QEMUGDB = $(shell if $(QEMU) -help | grep -q '^-gdb'; \
-	then echo "-gdb tcp::$(GDBPORT)"; \
-	else echo "-s -p $(GDBPORT)"; fi)
-ifndef CPUS
-CPUS := 3
-endif
-
-QEMUOPTS = -machine virt -bios none -kernel $K/kernel -m 128M -smp $(CPUS) -nographic
-QEMUOPTS += -global virtio-mmio.force-legacy=false
-QEMUOPTS += -drive file=fs.img,if=none,format=raw,id=x0
-QEMUOPTS += -device virtio-blk-device,drive=x0,bus=virtio-mmio-bus.0
-
 build: $K/kernel fs.img
 
-qemu: $K/kernel fs.img
-	$(QEMU) $(QEMUOPTS)
-
-.gdbinit: .gdbinit.tmpl-riscv
-	sed "s/:1234/:$(GDBPORT)/" < $^ > $@
-
-qemu-gdb: $K/kernel .gdbinit fs.img
-	@echo "*** Now run 'gdb' in another window." 1>&2
-	$(QEMU) $(QEMUOPTS) -S $(QEMUGDB)
-

lasoft/xv6-la/kernel/start.c

@@ -51,7 +51,7 @@ start()
   w_tp(id);
 
   // switch to supervisor mode and jump to main().
-  asm volatile("mret");
+  asm volatile("ertn");
 }
 
 // arrange to receive timer interrupts.