Merge pull request #353 from tianrui-wei/master

fix: fix icache_tb not finishing correctly

README.md

@@ -103,14 +103,8 @@ sudo dnf install fusesoc
 
 ```
 fusesoc init
-```
-
-- Create a working directory and point FuseSoC at microwatt:
-
-```
-mkdir microwatt-fusesoc
-cd microwatt-fusesoc
-fusesoc library add microwatt /path/to/microwatt/
+fusesoc fetch uart16550
+fusesoc library add microwatt /path/to/microwatt
 ```
 
 - Build using FuseSoC. For hello world (Replace nexys_video with your FPGA board such as --target=arty_a7-100):
@@ -128,6 +122,68 @@ You should then be able to see output via the serial port of the board (/dev/tty
 fusesoc run --target=nexys_video microwatt
 ```
 
+## Linux on Microwatt
+
+Mainline Linux supports Microwatt as of v5.14. The Arty A7 is the best tested
+platform, but it's also been tested on the OrangeCrab and ButterStick.
+
+1. Use buildroot to create a userspace
+
+   A small change is required to glibc in order to support the VMX/AltiVec-less
+   Microwatt, as float128 support is mandiatory and for this in GCC requires
+   VSX/AltiVec. This change is included in Joel's buildroot fork, along with a
+   defconfig:
+   ```
+   git clone -b microwatt https://github.com/shenki/buildroot
+   cd buildroot
+   make ppc64le_microwatt_defconfig
+   make
+   ```
+
+   The output is `output/images/rootfs.cpio`.
+
+2. Build the Linux kernel
+   ```
+   git clone https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
+   cd linux
+   make ARCH=powerpc microwatt_defconfig
+   make ARCH=powerpc CROSS_COMPILE=powerpc64le-linux-gnu- \
+     CONFIG_INITRAMFS_SOURCE=/buildroot/output/images/rootfs.cpio -j`nproc`
+   ```
+
+   The output is `arch/powerpc/boot/dtbImage.microwatt.elf`.
+
+3. Build gateware using FuseSoC
+
+   First configure FuseSoC as above.
+   ```
+   fusesoc run --build --target=arty_a7-100 microwatt --no_bram --memory_size=0
+   ```
+
+   The output is `build/microwatt_0/arty_a7-100-vivado/microwatt_0.bit`.
+
+4. Program the flash
+
+   This operation will overwrite the contents of your flash.
+
+   For the Arty A7 A100, set `FLASH_ADDRESS` to `0x400000` and pass `-f a100`.
+
+   For the Arty A7 A35, set `FLASH_ADDRESS` to `0x300000` and pass `-f a35`.
+   ```
+   microwatt/openocd/flash-arty -f a100 build/microwatt_0/arty_a7-100-vivado/microwatt_0.bit
+   microwatt/openocd/flash-arty -f a100 dtbImage.microwatt.elf -t bin -a $FLASH_ADDRESS
+   ```
+
+5. Connect to the second USB TTY device exposed by the FPGA
+
+   ```
+   minicom -D /dev/ttyUSB1
+   ```
+
+   The gateware has firmware that will look at `FLASH_ADDRESS` and attempt to
+   parse an ELF there, loading it to the address specified in the ELF header
+   and jumping to it.
+
 ## Testing
 
 - A simple test suite containing random execution test cases and a couple of

core.vhdl

@@ -117,7 +117,6 @@ architecture behave of core is
     signal complete: instr_tag_t;
     signal terminate: std_ulogic;
     signal core_rst: std_ulogic;
-    signal icache_inv: std_ulogic;
     signal do_interrupt: std_ulogic;
 
     -- Delayed/Latched resets and alt_reset

core_debug.vhdl

@@ -154,6 +154,7 @@ begin
                 stopping <= '0';
                 terminated <= '0';
                 log_trigger_delay <= 0;
+                gspr_index <= (others => '0');
             else
                 if do_log_trigger = '1' or log_trigger_delay /= 0 then
                     if log_trigger_delay = 255 then

dcache.vhdl

@@ -1121,7 +1121,6 @@ begin
     rams: for i in 0 to NUM_WAYS-1 generate
 	signal do_read  : std_ulogic;
 	signal rd_addr  : std_ulogic_vector(ROW_BITS-1 downto 0);
-	signal do_write : std_ulogic;
 	signal wr_addr  : std_ulogic_vector(ROW_BITS-1 downto 0);
 	signal wr_data  : std_ulogic_vector(wishbone_data_bits-1 downto 0);
 	signal wr_sel   : std_ulogic_vector(ROW_SIZE-1 downto 0);

execute1.vhdl

@@ -113,8 +113,6 @@ architecture behaviour of execute1 is
     signal misc_result: std_ulogic_vector(63 downto 0);
     signal muldiv_result: std_ulogic_vector(63 downto 0);
     signal spr_result: std_ulogic_vector(63 downto 0);
-    signal result_mux_sel: std_ulogic_vector(2 downto 0);
-    signal sub_mux_sel: std_ulogic_vector(2 downto 0);
     signal next_nia : std_ulogic_vector(63 downto 0);
     signal current: Decode2ToExecute1Type;
 

fpu.vhdl

@@ -549,6 +549,10 @@ begin
                 r.do_intr <= '0';
                 r.fpscr <= (others => '0');
                 r.writing_back <= '0';
+                r.dest_fpr <= (others =>'0');
+                r.cr_mask <= (others =>'0');
+                r.cr_result <= (others =>'0');
+                r.instr_tag.valid <= '0';
             else
                 assert not (r.state /= IDLE and e_in.valid = '1') severity failure;
                 r <= rin;

hello_world/head.S

@@ -60,11 +60,25 @@ _start:
 
 .global boot_entry
 boot_entry:
+	LOAD_IMM64(%r10,__bss_start)
+	LOAD_IMM64(%r11,__bss_end)
+	subf	%r11,%r10,%r11
+	addi	%r11,%r11,63
+	srdi.	%r11,%r11,6
+	beq	2f
+	mtctr	%r11
+1:	dcbz	0,%r10
+	addi	%r10,%r10,64
+	bdnz	1b
+
 	/* setup stack */
-	LOAD_IMM64(%r1, STACK_TOP - 0x100)
+2:	LOAD_IMM64(%r1,__stack_top)
+	li	%r0,0
+	stdu	%r0,-32(%r1)
 	LOAD_IMM64(%r12, main)
-	mtctr	%r12,
+	mtctr	%r12
 	bctrl
+	attn // terminate on exit
 	b .
 
 #define EXCEPTION(nr)		\

hello_world/hello_world.hex

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@@ -510,150 +510,150 @@ a64b5a7d14004a39
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hello_world/powerpc.lds

@@ -1,13 +1,27 @@
 SECTIONS
 {
-	_start = .;
 	. = 0;
+	_start = .;
 	.head : {
 		KEEP(*(.head))
 	}
 	. = 0x1000;
-	.text : { *(.text) }
+	.text : { *(.text) *(.text.*) *(.rodata) *(.rodata.*) }
 	. = 0x1800;
-	.data : { *(.data) }
-	.bss : { *(.bss) }
+	.data : { *(.data) *(.data.*) *(.got) *(.toc) }
+	. = ALIGN(0x80);
+	__bss_start = .;
+	.bss : {
+		*(.dynsbss)
+		*(.sbss)
+		*(.scommon)
+		*(.dynbss)
+		*(.bss)
+		*(.common)
+		*(.bss.*)
+	}
+	. = ALIGN(0x80);
+	__bss_end = .;
+	. = . + 0x2000;
+	__stack_top = .;
 }

icache.vhdl

@@ -555,7 +555,11 @@ begin
 	--       I prefer not to do just yet as it would force fetch2 to know about
 	--       some of the cache geometry information.
 	--
+	if r.hit_valid = '1' then
             i_out.insn <= read_insn_word(r.hit_nia, cache_out(r.hit_way));
+	else
+            i_out.insn <= (others => '0');
+	end if;
 	i_out.valid <= r.hit_valid;
 	i_out.nia <= r.hit_nia;
 	i_out.stop_mark <= r.hit_smark;
@@ -820,4 +824,7 @@ begin
         end process;
         log_out <= log_data;
     end generate;
+
+    events <= ev;
+
 end;

icache_tb.vhdl

@@ -74,6 +74,9 @@ begin
         i_out.req <= '0';
         i_out.nia <= (others => '0');
         i_out.stop_mark <= '0';
+        i_out.priv_mode <= '1';
+        i_out.virt_mode <= '0';
+        i_out.big_endian <= '0';
 
         m_out.tlbld <= '0';
         m_out.tlbie <= '0';

loadstore1.vhdl

@@ -275,10 +275,27 @@ begin
         if rising_edge(clk) then
             if rst = '1' then
                 r1.req.valid <= '0';
+                r1.req.tlbie <= '0';
+                r1.req.is_slbia <= '0';
+                r1.req.instr_fault <= '0';
+                r1.req.load <= '0';
+                r1.req.priv_mode <= '0';
+                r1.req.sprn <= (others => '0');
+                r1.req.xerc <= xerc_init;
+
                 r2.req.valid <= '0';
+                r2.req.tlbie <= '0';
+                r2.req.is_slbia <= '0';
+                r2.req.instr_fault <= '0';
+                r2.req.load <= '0';
+                r2.req.priv_mode <= '0';
+                r2.req.sprn <= (others => '0');
+                r2.req.xerc <= xerc_init;
+
                 r2.wait_dc <= '0';
                 r2.wait_mmu <= '0';
                 r2.one_cycle <= '0';
+
                 r3.dar <= (others => '0');
                 r3.dsisr <= (others => '0');
                 r3.state <= IDLE;