When this was merged in qemu-kvm/master (commit 6249f61a891b6b003531ca4e459c3a553faa82bc) it removed Avi's compile fix when !CONFIG_EVENTFD (db311e8619d310bd7729637b702581d3d8565049).
So current master fails to build:
CC osdep.o
cc1: warnings being treated as errors
osdep.c: In function 'qemu_eventfd':
osdep.c:296: error: unused variable 'ret'
make: *** [osdep.o] Error 1
On 22 févr. 2010, at 22:26, Marcelo Tosatti wrote:
> From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Signed-off-by: Avi Kivity <avi@xxxxxxxxxx>
> ---
> osdep.c | 32 ++++++++++++++++++++++++++++++++
> qemu-common.h | 1 +
> vl.c | 9 +++++----
> 3 files changed, 38 insertions(+), 4 deletions(-)
>
> diff --git a/osdep.c b/osdep.c
> index 9059f01..9e4b17b 100644
> --- a/osdep.c
> +++ b/osdep.c
> @@ -37,6 +37,10 @@
> #include <sys/statvfs.h>
> #endif
>
> +#ifdef CONFIG_EVENTFD
> +#include <sys/eventfd.h>
> +#endif
> +
> #ifdef _WIN32
> #include <windows.h>
> #elif defined(CONFIG_BSD)
> @@ -281,6 +285,34 @@ ssize_t qemu_write_full(int fd, const void *buf, size_t count)
>
> #ifndef _WIN32
> /*
> + * Creates an eventfd that looks like a pipe and has EFD_CLOEXEC set.
> + */
> +int qemu_eventfd(int fds[2])
> +{
> + int ret;
> +
> +#ifdef CONFIG_EVENTFD
> + ret = eventfd(0, 0);
> + if (ret >= 0) {
> + fds[0] = ret;
> + qemu_set_cloexec(ret);
> + if ((fds[1] = dup(ret)) == -1) {
> + close(ret);
> + return -1;
> + }
> + qemu_set_cloexec(fds[1]);
> + return 0;
> + }
> +
> + if (errno != ENOSYS) {
> + return -1;
> + }
> +#endif
> +
> + return qemu_pipe(fds);
> +}
> +
> +/*
> * Creates a pipe with FD_CLOEXEC set on both file descriptors
> */
> int qemu_pipe(int pipefd[2])
> diff --git a/qemu-common.h b/qemu-common.h
> index b09f717..c941006 100644
> --- a/qemu-common.h
> +++ b/qemu-common.h
> @@ -170,6 +170,7 @@ ssize_t qemu_write_full(int fd, const void *buf, size_t count)
> void qemu_set_cloexec(int fd);
>
> #ifndef _WIN32
> +int qemu_eventfd(int pipefd[2]);
> int qemu_pipe(int pipefd[2]);
> #endif
>
> diff --git a/vl.c b/vl.c
> index 98918ac..1957018 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -3211,14 +3211,15 @@ static int io_thread_fd = -1;
>
> static void qemu_event_increment(void)
> {
> - static const char byte = 0;
> + /* Write 8 bytes to be compatible with eventfd. */
> + static uint64_t val = 1;
> ssize_t ret;
>
> if (io_thread_fd == -1)
> return;
>
> do {
> - ret = write(io_thread_fd, &byte, sizeof(byte));
> + ret = write(io_thread_fd, &val, sizeof(val));
> } while (ret < 0 && errno == EINTR);
>
> /* EAGAIN is fine, a read must be pending. */
> @@ -3235,7 +3236,7 @@ static void qemu_event_read(void *opaque)
> ssize_t len;
> char buffer[512];
>
> - /* Drain the notify pipe */
> + /* Drain the notify pipe. For eventfd, only 8 bytes will be read. */
> do {
> len = read(fd, buffer, sizeof(buffer));
> } while ((len == -1 && errno == EINTR) || len == sizeof(buffer));
> @@ -3246,7 +3247,7 @@ static int qemu_event_init(void)
> int err;
> int fds[2];
>
> - err = qemu_pipe(fds);
> + err = qemu_eventfd(fds);
> if (err == -1)
> return -errno;
>
> --
> 1.6.6
>
> --
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--
Pierre Riteau -- PhD student, Myriads team, IRISA, Rennes, France
http://perso.univ-rennes1.fr/pierre.riteau/
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