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[Qemu-devel] [PATCH 4/5] I/O vector helpers
From: |
Avi Kivity |
Subject: |
[Qemu-devel] [PATCH 4/5] I/O vector helpers |
Date: |
Sun, 18 Jan 2009 21:53:18 +0200 |
In general, it is not possible to predict the size of of an I/O vector since
a contiguous guest region may map to a disconiguous host region. Add some
helpers to manage I/O vector growth.
Signed-off-by: Avi Kivity <address@hidden>
---
qemu-common.h | 10 ++++++++++
vl.c | 25 +++++++++++++++++++++++++
2 files changed, 35 insertions(+), 0 deletions(-)
diff --git a/qemu-common.h b/qemu-common.h
index d83e61b..1a746f9 100644
--- a/qemu-common.h
+++ b/qemu-common.h
@@ -191,6 +191,16 @@ int cpu_load(QEMUFile *f, void *opaque, int version_id);
/* Force QEMU to stop what it's doing and service IO */
void qemu_service_io(void);
+typedef struct QEMUIOVector {
+ struct iovec *iov;
+ int niov;
+ int nalloc;
+} QEMUIOVector;
+
+void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint);
+void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len);
+void qemu_iovec_destroy(QEMUIOVector *qiov);
+
#endif /* dyngen-exec.h hack */
#endif
diff --git a/vl.c b/vl.c
index 34ddc07..7ceedd4 100644
--- a/vl.c
+++ b/vl.c
@@ -3344,6 +3344,31 @@ static void qemu_bh_update_timeout(int *timeout)
}
}
+/* io vectors */
+
+void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint)
+{
+ qiov->iov = qemu_malloc(alloc_hint * sizeof(struct iovec));
+ qiov->niov = 0;
+ qiov->nalloc = alloc_hint;
+}
+
+void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len)
+{
+ if (qiov->niov == qiov->nalloc) {
+ qiov->nalloc = 2 * qiov->nalloc + 1;
+ qiov->iov = qemu_realloc(qiov->iov, qiov->nalloc * sizeof(struct
iovec));
+ }
+ qiov->iov[qiov->niov].iov_base = base;
+ qiov->iov[qiov->niov].iov_len = len;
+ ++qiov->niov;
+}
+
+void qemu_iovec_destroy(QEMUIOVector *qiov)
+{
+ qemu_free(qiov->iov);
+}
+
/***********************************************************/
/* machine registration */
--
1.6.0.6