Add csrtool to view and change CSR registers

JOURNAL.md

@@ -885,3 +885,8 @@ Continues to hang just after those perl messages:
 
 May be a long shot, but if we are experiencing the same page fault loop as in
 cincoranch we may as well try.
+
+### QUESTION: Maybe we can try without out-of-order?
+
+I made a small tool in C to view and change the CSR register that controls the
+in-order/out-of-order. Maybe we can try with the "in-order" setting.

csrtool.c

@@ -0,0 +1,34 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int main(int argc, char *argv[])
+{
+	/* Print */
+	if (argc > 1) {
+		// Wait for all memory operations to finish
+		__asm__ volatile ("fence");
+
+		if (strcmp(argv[1], "mem-in-order") == 0) {
+			__asm__ volatile ("fence");
+			__asm__ volatile ("csrwi  0x801, 2");
+		} else if (strcmp(argv[1], "all-in-order") == 0) {
+			__asm__ volatile ("fence");
+			__asm__ volatile ("csrwi  0x801, 7");
+		} else if (strcmp(argv[1], "all-out-of-order") == 0) {
+			__asm__ volatile ("fence");
+			__asm__ volatile ("csrwi  0x801, 0");
+		} else {
+			fprintf(stderr, "unknown '%s', use: mem-in-order, all-in-order or all-out-of-order\n", argv[1]);
+			exit(1);
+		}
+	}
+
+	// Wait for all memory operations to finish
+	__asm__ volatile ("fence");
+	unsigned result;
+	asm("csrr %0, 0x801" : "=r"(result) : );
+	printf("CSR 0x801 = %xu\n", result);
+
+	return 0;
+}

lagarto-ox.nix

@@ -81,6 +81,12 @@
       compressor = "gzip";
       kernelModules = [ ];
 
+      # Add the csrtool to the initrd so we can change the
+      # in-order/out-of-order.
+      extraUtilsCommands = ''
+        cp -a ${pkgs.csrtool}/bin/csrtool $out/bin
+      '';
+
       # Write a counter to the DMA region, so we can check the kernel is not
       # dead. Monitor from the host with:
       # while [ 1 ]; do xxd -s $((0x1bfff0000 - 0x60000000)) \

overlay.nix

@@ -37,6 +37,22 @@ final: prev:
     '';
   };
 
+  csrtool = prev.pkgsStatic.stdenv.mkDerivation {
+    name = "csrtool";
+    src = ./csrtool.c;
+    unpackPhase = ''
+      cp ${./csrtool.c} csrtool.c
+    '';
+    dontConfigure = true;
+    buildPhase = ''
+      $CC -static csrtool.c -o csrtool
+    '';
+    installPhase = ''
+      mkdir -p $out/bin
+      cp csrtool $out/bin/
+    '';
+  };
+
   bitstreams = builtins.fetchGit {
     url = "git@bscpm03.bsc.es:rarias/bitstreams.git";
     rev = "ad901b0c21ffbdb310ff1dfb269f169f6ac6bde6";