vio_iov
Structure for converting a virtqueue descriptor list into an iov_t array
Synopsis:
#include <qvm/vio.h>struct vio_iov {
iov_t *vi_iov;
struct __iovec64 *vi_paddrs;
int vi_iov_len;
int vi_reserved;
vio_iov_flags_t vi_flags;
unsigned vi_hdr_len;
int vi_count;
int vi_payload;
iov_postmap_elem_t *vi_is_postmap;
};Data:
- iov_t* vi_iov
- The actual I/O vector.
- struct __iovec64* vi_paddrs
- The physical addresses, if requested.
- int vi_iov_len
- The size of the array allocated in vi_iov.
- int vi_reserved
- The number of entries to reserve for the caller's use.
- vio_iov_flags_t vi_flags
- A VVF_* value that specifies whether a host-physical address is required.
- unsigned vi_hdr_len
- The size of the expected header.
- int vi_count
- The number of entries mapped in vi_iov.
- int vi_payload
- The index at which the payload starts.
- iov_postmap_elem_t* vi_is_postmap
- An array that stores a mmap() status for each vi_iov entry.
Description:
The vio_iov data type is used for converting a virtqueue descriptor list into an iov_t array. The vdev will likely re-use a vio_iov structure for multiple calls to vio_get_iov().
The vi_hdr_len member is usually expected to be constant through the life of the current structure. It is usually best to set its value immediately after initially zeroing the structure.
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