[Qemu-devel] [PATCH 17/32] build list of available accelerators

[Glauber Costa]

From: Glauber Costa <address@hidden>

instead of hardcoding kqemu_start() in exec.c, which would require
such a hack for all available accelerators, semantics of register_qemu_accel()
is changed a little bit. It only builds a list of available accelerators.
The last one registered is the first tried.

This is a temporary solution, since we don't control exactly the order in which
things are loaded by the constructor attributes. The final goal is to have 
command
line switches and priority lists to determine that.

"info accelerator" is changed to accomodate it. It now prints a list of 
available
accelerators, and only if one of them is active, a detailed description of it 
is printed.

Signed-off-by: Glauber Costa <address@hidden>
Signed-off-by: Jes Sorensen <address@hidden>
---
 accel.c   |    3 ++
 accel.h   |   63 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 exec.c    |    3 --
 kqemu.c   |    5 ++-
 monitor.c |   12 +++++++++-
 vl.c      |    7 ++++++
 6 files changed, 84 insertions(+), 9 deletions(-)

diff --git a/accel.c b/accel.c
index 08a85c2..74f7c89 100644
--- a/accel.c
+++ b/accel.c
@@ -2,6 +2,7 @@
 #include "accel.h"
 
 QEMUAccel *current_accel;
+QEMUCont *head = NULL;
 
 int _accel_nop(void)
 {
@@ -17,8 +18,10 @@ int noaccel_info(CPUState *env, char *buf)
 
 /* Accelerator wrapper for the no-accel (raw qemu) case */
 QEMUAccel noaccel = {
+    .name = "none",
     .cpu_interrupt = accel_nop,
     .init_env = accel_nop,
+    .start = accel_nop,
     .flush_cache = accel_nop,
     .flush_page = accel_nop,
     .info = noaccel_info,
diff --git a/accel.h b/accel.h
index cf0d752..3e49a93 100644
--- a/accel.h
+++ b/accel.h
@@ -4,8 +4,10 @@
 #define MAX_INFO_BUF 1024
 
 typedef struct QEMUAccel {
+    char *name;
     void (*cpu_interrupt)(CPUState *env);
     void (*init_env)(CPUState *env);
+    int (*start)(int cpus);
     void (*flush_cache)(CPUState *env, int global);
     void (*flush_page)(CPUState *env, target_ulong addr);
     int (*info)(CPUState *env, char *buf);
@@ -17,12 +19,51 @@ typedef struct QEMUAccel {
 #endif
 } QEMUAccel;
 
+typedef struct QEMUCont {
+    QEMUAccel *acc;
+    int active;
+    struct QEMUCont *next;
+} QEMUCont;
+
 extern QEMUAccel *current_accel;
 extern QEMUAccel noaccel;
+#ifdef USE_KQEMU
+extern QEMUAccel kqemu_accel;
+#endif
 
-static inline void register_qemu_accel(QEMUAccel *accel)
+extern QEMUCont *head;
+void *qemu_mallocz(size_t size);
+
+static inline int register_qemu_accel(QEMUAccel *accel)
 {
-    current_accel = accel;
+    QEMUCont *new, *tmp, *last = NULL;
+
+    for (tmp = head, last; tmp; tmp = tmp->next) {
+        /* we disallow registering the same accelerator twice */
+        if (tmp->acc ==  accel)
+            return -1;
+
+        if (!tmp->next)
+            last = tmp;
+    }
+
+    new = qemu_mallocz(sizeof(*head));
+
+    new->acc = accel;
+    new->active = 0;
+    new->next = NULL;
+
+    if (!head)
+        head = new;
+    else
+        last->next = new;
+
+    return 0;
+}
+
+static inline QEMUCont *get_accel_head(void)
+{
+    return head;
 }
 
 static inline void accel_cpu_interrupt(CPUState *env)
@@ -30,6 +71,24 @@ static inline void accel_cpu_interrupt(CPUState *env)
     current_accel->cpu_interrupt(env);
 }
 
+static inline int accel_start(int cpus)
+{
+    int status = -1;
+    /* The top accelerator in the list gets tried first, but if it fails,
+     * keep trying until one of them succeeds or we exhaust the list */
+    QEMUCont *tmp = head;
+    while (tmp) {
+        if (tmp->acc && tmp->acc->start && (!(tmp->acc->start(cpus))) ) {
+            tmp->active = 1;
+            current_accel = tmp->acc;
+            status = 0;
+            break;
+        }
+        tmp = tmp->next;
+    }
+    return status;
+}
+
 static inline void accel_init_env(CPUState *env)
 {
     current_accel->init_env(env);
diff --git a/exec.c b/exec.c
index 089a91e..005785a 100644
--- a/exec.c
+++ b/exec.c
@@ -497,9 +497,6 @@ void cpu_exec_init_all(unsigned long tb_size)
 #if !defined(CONFIG_USER_ONLY)
     io_mem_init();
 #endif
-#ifdef USE_KQEMU
-    kqemu_start();
-#endif
 }
 
 #if defined(CPU_SAVE_VERSION) && !defined(CONFIG_USER_ONLY)
diff --git a/kqemu.c b/kqemu.c
index 6bce892..68ec917 100644
--- a/kqemu.c
+++ b/kqemu.c
@@ -158,7 +158,7 @@ static void kqemu_update_cpuid(CPUState *env)
 
 QEMUAccel kqemu_accel;
 
-int kqemu_start(void)
+static int kqemu_start(int cpus)
 {
     struct kqemu_init kinit;
     int ret, version;
@@ -240,7 +240,6 @@ int kqemu_start(void)
     }
     nb_pages_to_flush = 0;
     nb_ram_pages_to_update = 0;
-    register_qemu_accel(&kqemu_accel);
 
     qpi_init();
     return 0;
@@ -1109,8 +1108,10 @@ static int kqemu_profile(CPUState *env, char *buf)
 }
 
 QEMUAccel kqemu_accel = {
+    .name = "KQEMU",
     .cpu_interrupt = kqemu_cpu_interrupt,
     .init_env = kqemu_init_env,
+    .start = kqemu_start,
     .flush_cache = kqemu_flush,
     .flush_page = kqemu_flush_page,
     .info = kqemu_info,
diff --git a/monitor.c b/monitor.c
index 42a1b02..fe915d8 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1234,6 +1234,15 @@ static void mem_info(void)
 }
 #endif
 
+static int do_accel_do_list(void)
+{
+    QEMUCont *tmp;
+    for (tmp= get_accel_head(); tmp != NULL; tmp = tmp->next)
+    {
+        term_printf("%c %s\n", tmp->active ? '*' : ' ', tmp->acc->name);
+    }
+}
+
 static void do_info_accelerator(void)
 {
     char buf[MAX_INFO_BUF];
@@ -1246,10 +1255,9 @@ static void do_info_accelerator(void)
         return;
     }
 
+    do_accel_do_list();
     if (accel_info(env, buf))
         term_printf(buf);
-    else
-        term_printf("No accelerator present\n");
 }
 
 #ifdef CONFIG_PROFILER
diff --git a/vl.c b/vl.c
index f7bbfbb..c584ea3 100644
--- a/vl.c
+++ b/vl.c
@@ -140,6 +140,7 @@
 #include "disas.h"
 
 #include "exec-all.h"
+#include "accel.h"
 
 #define DEFAULT_NETWORK_SCRIPT "/etc/qemu-ifup"
 #define DEFAULT_NETWORK_DOWN_SCRIPT "/etc/qemu-ifdown"
@@ -8815,6 +8816,7 @@ int main(int argc, char **argv)
     }
 #endif
 
+    register_qemu_accel(&kqemu_accel);
     register_qemu_accel(&noaccel);
 
     register_machines();
@@ -9589,6 +9591,11 @@ int main(int argc, char **argv)
     /* init the dynamic translator */
     cpu_exec_init_all(tb_size * 1024 * 1024);
 
+    if (accel_start(smp_cpus)) {
+           fprintf(stderr, "qemu: error, no suitable accelerator found\n");
+           exit(1);
+    }
+
     bdrv_init();
 
     /* we always create the cdrom drive, even if no disk is there */
-- 
1.5.5.1