[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Qemu-devel] [PATCH 08/28] virtio-pci: Disable virtio-ioeventfd when !CO
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] [PATCH 08/28] virtio-pci: Disable virtio-ioeventfd when !CONFIG_IOTHREAD |
Date: |
Mon, 31 Jan 2011 16:28:56 +0100 |
From: Stefan Hajnoczi <address@hidden>
It is not possible to use virtio-ioeventfd when building without an I/O
thread. We rely on a signal to kick us out of vcpu execution. Timers
and AIO use SIGALRM and SIGUSR2 respectively. Unfortunately eventfd
does not support O_ASYNC (SIGIO) so eventfd cannot be used in a signal
driven manner.
Signed-off-by: Stefan Hajnoczi <address@hidden>
Acked-by: Michael S. Tsirkin <address@hidden>
Signed-off-by: Kevin Wolf <address@hidden>
---
kvm-all.c | 8 ++++++--
1 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/kvm-all.c b/kvm-all.c
index 255b6fa..8f0e17c 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -449,10 +449,14 @@ int kvm_check_extension(KVMState *s, unsigned int
extension)
static int kvm_check_many_ioeventfds(void)
{
- /* Older kernels have a 6 device limit on the KVM io bus. Find out so we
+ /* Userspace can use ioeventfd for io notification. This requires a host
+ * that supports eventfd(2) and an I/O thread; since eventfd does not
+ * support SIGIO it cannot interrupt the vcpu.
+ *
+ * Older kernels have a 6 device limit on the KVM io bus. Find out so we
* can avoid creating too many ioeventfds.
*/
-#ifdef CONFIG_EVENTFD
+#if defined(CONFIG_EVENTFD) && defined(CONFIG_IOTHREAD)
int ioeventfds[7];
int i, ret = 0;
for (i = 0; i < ARRAY_SIZE(ioeventfds); i++) {
--
1.7.2.3
- [Qemu-devel] [PULL 00/28] Block patches, Kevin Wolf, 2011/01/31
- [Qemu-devel] [PATCH 01/28] strtosz(): use unsigned char and switch to qemu_isspace(), Kevin Wolf, 2011/01/31
- [Qemu-devel] [PATCH 04/28] strtosz(): Use suffix macros in switch() statement, Kevin Wolf, 2011/01/31
- [Qemu-devel] [PATCH 02/28] strtosz() use qemu_toupper() to simplify switch statement, Kevin Wolf, 2011/01/31
- [Qemu-devel] [PATCH 07/28] virtio-blk: tell the guest about size changes, Kevin Wolf, 2011/01/31
- [Qemu-devel] [PATCH 03/28] strtosz(): Fix name confusion in use of modf(), Kevin Wolf, 2011/01/31
- [Qemu-devel] [PATCH 12/28] sheepdog: support creating images on remote hosts, Kevin Wolf, 2011/01/31
- [Qemu-devel] [PATCH 05/28] block: add block_resize monitor command, Kevin Wolf, 2011/01/31
- [Qemu-devel] [PATCH 08/28] virtio-pci: Disable virtio-ioeventfd when !CONFIG_IOTHREAD,
Kevin Wolf <=
- [Qemu-devel] [PATCH 10/28] ahci: Fix cpu_physical_memory_unmap() argument ordering, Kevin Wolf, 2011/01/31
- [Qemu-devel] [PATCH 18/28] qcow2-refcount: remove write-only variables, Kevin Wolf, 2011/01/31
- [Qemu-devel] [PATCH 15/28] qed: Images with backing file do not require QED_F_NEED_CHECK, Kevin Wolf, 2011/01/31
- [Qemu-devel] [PATCH 11/28] Reorganize struct Qcow2Cache for better struct packing, Kevin Wolf, 2011/01/31
- [Qemu-devel] [PATCH 14/28] qcow2: Add bdrv_discard support, Kevin Wolf, 2011/01/31
- [Qemu-devel] [PATCH 17/28] scsi hotplug: Set DriveInfo member bus correctly, Kevin Wolf, 2011/01/31
- [Qemu-devel] [PATCH 16/28] raw-win32: Fix bdrv_flush return value, Kevin Wolf, 2011/01/31
- [Qemu-devel] [PATCH 24/28] blockdev: Factor drive_index_to_{bus, unit}_id out of drive_init(), Kevin Wolf, 2011/01/31
- [Qemu-devel] [PATCH 27/28] blockdev: Replace drive_add()'s fmt, ... by optstr parameter, Kevin Wolf, 2011/01/31
- [Qemu-devel] [PATCH 25/28] blockdev: New drive_get_by_index(), Kevin Wolf, 2011/01/31