Re: [Qemu-devel] [PATCH] use SIGALRM for alarm timers, enable SIGIO on qemu_set_fd_handler2()

[Anders Melchiorsen]

Jamie Lokier <address@hidden> writes:

> Anders Melchiorsen wrote:
>> -    sigaction(SIGIO, &act, NULL);
>> +    sigaction(SIGALRM, &act, NULL);
>>      fcntl(fd, F_SETFL, O_ASYNC);
>> +    fcntl(fd, F_SETSIG, SIGALRM);
>>      fcntl(fd, F_SETOWN, getpid());
>
> F_SETSIG is specific to Linux.  Other host OSes don't have it.

True, and actually it is flagged as such. The function is only called
from the Linux specific timers (hpet/rtc).

I did, however, place the enable_sigio() function inside the same
Linux-only part as well. Here is an update where it is moved out (but
still not into WIN32).


Thanks,
Anders



diff --git a/vl.c b/vl.c
index 61eb191..dc4c5aa 100644
--- a/vl.c
+++ b/vl.c
@@ -1148,6 +1148,25 @@ static int timer_load(QEMUFile *f, void *opaque, int 
version_id)
     return 0;
 }
 
+#ifndef _WIN32
+static void host_io_handler(int host_signum)
+{
+    CPUState *env = next_cpu;
+
+    if (env) {
+        /* stop the currently executing cpu because io occured */
+        cpu_interrupt(env, CPU_INTERRUPT_EXIT);
+#ifdef USE_KQEMU
+        if (env->kqemu_enabled) {
+            kqemu_cpu_interrupt(env);
+        }
+#endif
+    }
+
+    event_pending = 1;
+}
+#endif
+
 #ifdef _WIN32
 void CALLBACK host_alarm_handler(UINT uTimerID, UINT uMsg,
                                  DWORD_PTR dwUser, DWORD_PTR dw1, DWORD_PTR 
dw2)
@@ -1236,11 +1255,24 @@ static uint64_t qemu_next_deadline(void)
 
 #ifndef _WIN32
 
+static void enable_sigio(int fd)
+{
+    struct sigaction act;
+
+    sigfillset(&act.sa_mask);
+    act.sa_flags = 0;
+    act.sa_handler = host_io_handler;
+
+    sigaction(SIGIO, &act, NULL);
+    fcntl(fd, F_SETFL, O_ASYNC|O_NONBLOCK);
+    fcntl(fd, F_SETOWN, getpid());
+}
+
 #if defined(__linux__)
 
 #define RTC_FREQ 1024
 
-static void enable_sigio_timer(int fd)
+static void enable_sigalrm(int fd)
 {
     struct sigaction act;
 
@@ -1249,8 +1281,9 @@ static void enable_sigio_timer(int fd)
     act.sa_flags = 0;
     act.sa_handler = host_alarm_handler;
 
-    sigaction(SIGIO, &act, NULL);
+    sigaction(SIGALRM, &act, NULL);
     fcntl(fd, F_SETFL, O_ASYNC);
+    fcntl(fd, F_SETSIG, SIGALRM);
     fcntl(fd, F_SETOWN, getpid());
 }
 
@@ -1287,7 +1320,7 @@ static int hpet_start_timer(struct qemu_alarm_timer *t)
     if (r < 0)
         goto fail;
 
-    enable_sigio_timer(fd);
+    enable_sigalrm(fd);
     t->priv = (void *)(long)fd;
 
     return 0;
@@ -1325,7 +1358,7 @@ static int rtc_start_timer(struct qemu_alarm_timer *t)
         return -1;
     }
 
-    enable_sigio_timer(rtc_fd);
+    enable_sigalrm(rtc_fd);
 
     t->priv = (void *)(long)rtc_fd;
 
@@ -5519,6 +5552,10 @@ int qemu_set_fd_handler2(int fd,
             return -1;
         ioh->next = first_io_handler;
         first_io_handler = ioh;
+#ifndef _WIN32
+        enable_sigio(fd);
+#endif
+
     found:
         ioh->fd = fd;
         ioh->fd_read_poll = fd_read_poll;