[Qemu-devel] [PATCH] Add option to disable TB cache

[Qemu-devel] [PATCH] Add option to disable TB cache

[Hervé Poussineau]

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Hi,
  
This patch adds the "-translation no-cache" option to disable the use 
of Translation Blocks Cache.
The emulated system runs much slower, but it is easier to debug it. The 
-translation value can be extended to handle more settings.
  
It also adds help for "-startdate" flag and displays right log file 
name.
  
Hervé


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Index: cpu-all.h
===================================================================
RCS file: /sources/qemu/qemu/cpu-all.h,v
retrieving revision 1.81
diff -u -r1.81 cpu-all.h
--- cpu-all.h	1 Jan 2008 16:57:19 -0000	1.81
+++ cpu-all.h	8 Jan 2008 16:41:09 -0000
@@ -787,6 +787,20 @@
 void cpu_set_log_filename(const char *filename);
 int cpu_str_to_log_mask(const char *str);
 
+#define CPU_SETTING_NO_CACHE (1 << 0)
+
+/* define translation settings */
+typedef struct CPUTranslationSetting {
+    int mask;
+    const char *name;
+    const char *help;
+} CPUTranslationSetting;
+
+extern CPUTranslationSetting cpu_translation_settings[];
+
+void cpu_set_translation_settings(int translation_flags);
+int cpu_str_to_translation_mask(const char *str);
+
 /* IO ports API */
 
 /* NOTE: as these functions may be even used when there is an isa
Index: cpu-exec.c
===================================================================
RCS file: /sources/qemu/qemu/cpu-exec.c,v
retrieving revision 1.130
diff -u -r1.130 cpu-exec.c
--- cpu-exec.c	11 Dec 2007 19:39:25 -0000	1.130
+++ cpu-exec.c	8 Jan 2008 16:52:33 -0000
@@ -20,6 +20,7 @@
 #include "config.h"
 #include "exec.h"
 #include "disas.h"
+#include <string.h>
 
 #if !defined(CONFIG_SOFTMMU)
 #undef EAX
@@ -40,6 +41,9 @@
 //#define DEBUG_EXEC
 //#define DEBUG_SIGNAL
 
+/* translation settings */
+int translation_settings = 0;
+
 #define SAVE_GLOBALS()
 #define RESTORE_GLOBALS()
 
@@ -120,6 +124,56 @@
     longjmp(env->jmp_env, 1);
 }
 
+CPUTranslationSetting cpu_translation_settings[] = {
+    { CPU_SETTING_NO_CACHE, "no-cache",
+      "Do not use translation blocks cache (very slow!)" },
+    { 0, NULL, NULL },
+};
+
+void cpu_set_translation_settings(int translation_flags)
+{
+    translation_settings = translation_flags;
+}
+
+static int cmp1(const char *s1, int n, const char *s2)
+{
+    if (strlen(s2) != n)
+        return 0;
+    return memcmp(s1, s2, n) == 0;
+}
+
+/* takes a comma separated list of translation settings. Return 0 if error. */
+int cpu_str_to_translation_mask(const char *str)
+{
+    CPUTranslationSetting *setting;
+    int mask;
+    const char *p, *p1;
+
+    p = str;
+    mask = 0;
+    for(;;) {
+        p1 = strchr(p, ',');
+        if (!p1)
+            p1 = p + strlen(p);
+        if(cmp1(p,p1-p,"all")) {
+            for(setting = cpu_translation_settings; setting->mask != 0; setting++) {
+                mask |= setting->mask;
+            }
+        } else {
+            for(setting = cpu_translation_settings; setting->mask != 0; setting++) {
+                if (cmp1(p, p1 - p, setting->name))
+                    goto found;
+            }
+            return 0;
+        }
+    found:
+        mask |= setting->mask;
+        if (*p1 != ',')
+            break;
+        p = p1 + 1;
+    }
+    return mask;
+}
 
 static TranslationBlock *tb_find_slow(target_ulong pc,
                                       target_ulong cs_base,
@@ -141,6 +195,9 @@
     phys_pc = get_phys_addr_code(env, pc);
     phys_page1 = phys_pc & TARGET_PAGE_MASK;
     phys_page2 = -1;
+    if (translation_settings & CPU_SETTING_NO_CACHE)
+        goto not_found;
+
     h = tb_phys_hash_func(phys_pc);
     ptb1 = &tb_phys_hash[h];
     for(;;) {
@@ -264,7 +321,10 @@
 #else
 #error unsupported CPU
 #endif
-    tb = env->tb_jmp_cache[tb_jmp_cache_hash_func(pc)];
+    if (translation_settings & CPU_SETTING_NO_CACHE)
+        tb = NULL;
+    else
+        tb = env->tb_jmp_cache[tb_jmp_cache_hash_func(pc)];
     if (__builtin_expect(!tb || tb->pc != pc || tb->cs_base != cs_base ||
                          tb->flags != flags, 0)) {
         tb = tb_find_slow(pc, cs_base, flags);
Index: vl.c
===================================================================
RCS file: /sources/qemu/qemu/vl.c,v
retrieving revision 1.394
diff -u -r1.394 vl.c
--- vl.c	6 Jan 2008 17:21:48 -0000	1.394
+++ vl.c	8 Jan 2008 16:48:45 -0000
@@ -237,6 +237,8 @@
 static CPUState *next_cpu;
 static int event_pending = 1;
 
+extern char *logfilename;
+
 #define TFR(expr) do { if ((expr) != -1) break; } while (errno == EINTR)
 
 /***********************************************************/
@@ -7617,6 +7617,9 @@
 #endif
            "-clock          force the use of the given methods for timer alarm.\n"
            "                To see what timers are available use -clock help\n"
+           "-startdate      select initial date of the Qemu clock\n"
+           "-translation setting1,... configures code translation\n"
+           "                (use -translation ? for a list of settings)\n"
            "\n"
            "During emulation, the following keys are useful:\n"
            "ctrl-alt-f      toggle full screen\n"
@@ -7632,7 +7635,7 @@
            DEFAULT_NETWORK_DOWN_SCRIPT,
 #endif
            DEFAULT_GDBSTUB_PORT,
-           "/tmp/qemu.log");
+           logfilename);
     exit(exitcode);
 }
 
@@ -7719,6 +7722,7 @@
     QEMU_OPTION_old_param,
     QEMU_OPTION_clock,
     QEMU_OPTION_startdate,
+    QEMU_OPTION_translation,
 };
 
 typedef struct QEMUOption {
@@ -7827,6 +7831,7 @@
 #endif
     { "clock", HAS_ARG, QEMU_OPTION_clock },
     { "startdate", HAS_ARG, QEMU_OPTION_startdate },
+    { "translation", HAS_ARG, QEMU_OPTION_translation },
     { NULL },
 };
 
@@ -8661,6 +8666,22 @@
                     }
                 }
                 break;
+            case QEMU_OPTION_translation:
+                {
+                    int mask;
+                    CPUTranslationSetting *setting;
+
+                    mask = cpu_str_to_translation_mask(optarg);
+                    if (!mask) {
+                        printf("Translation settings (comma separated):\n");
+                        for(setting = cpu_translation_settings; setting->mask != 0; setting++) {
+                            printf("%-10s %s\n", setting->name, setting->help);
+                    }
+                    exit(1);
+                    }
+                    cpu_set_translation_settings(mask);
+                }
+                break;
             }
         }
     }