Jack Morgenstein wrote:
Actually, we did not break the ABI for XRC (we had to do cartwheels to avoid
this, but what the heck).
The create_flags field was added ONLY to struct ib_qp_init_attr (kernel only),
and was not exported upwards to the userspace API (so as not to break the ABI).
I got around the create_flags problem by adding a new verb to userspace
(ibv_create_xrc_rcv_qp() ) with its own ABI to kernel space. Since the kernel space
function (added to uverbs_cmd: ib_uverbs_create_xrc_rcv_qp() ) "knew" that it
was creating an XRC_RCV qp, it set the flag in ib_qp_init_attr appropriately.
Additionally, Eli did not need user-space involvement for his LSO flag -- so we
escaped needing to increment the ABI version number.
If we need to use the create_flags field in userspace, we WILL need to break
the ABI.
You can avoid doing this in one of 2 ways:
Either: create a new QP type
Or: add new verbs to the core.
Jack,
I am trying to figure out what would be the least painful way to allow
for specifi
Looking on the libibverbs - XRC instance
(git://git.openfabrics.org/ofed_1_3/libibverbs.git) and re-reading your
email, my understanding is that the way you went was
1. add a new field at the end of struct ibv_qp_init_attr
2. add bunch of new XRC verbs packed in struct ibv_xrc_ops
3. both create_qp & create_xrc_rcv_qp get ibv_qp_init_attr, the latter
looks on the xrc field
4. add ibv_xrc_ops at the end of the ibv_context
I have pasted below the relevant code from verbs.h, as I can't point on
one patch that does this all, since there were some fixes/changes since
the initial commit.
So if we want to have qp creation verb that gets creation flags, we can can
A. add create_flags field to the end of ibv_qp_init_attr
B. introduce struct ibv_qp * (*create_qp_ext)(struct ibv_pd *pd, struct
ibv_qp_init_attr *attr)
C. enhance struct ibv_context similarily to what was done for xrc
This seems to bring to minimum the breakage from the perspective of
libibverbs consumers.
As for taking this down to uverbs, I am fine with anything you suggest.
Or.
struct ibv_qp_init_attr {
void *qp_context;
struct ibv_cq *send_cq;
struct ibv_cq *recv_cq;
struct ibv_srq *srq;
struct ibv_qp_cap cap;
enum ibv_qp_type qp_type;
int sq_sig_all;
struct ibv_xrc_domain *xrc_domain;
};
struct ibv_qp * (*create_qp)(struct ibv_pd *pd, struct ibv_qp_init_attr *attr);
struct ibv_xrc_ops {
...
int (*create_xrc_rcv_qp)(struct ibv_qp_init_attr *init_attr, uint32_t
*xrc_qp_num);
...
};
struct ibv_context {
struct ibv_device *device;
struct ibv_context_ops ops;
int cmd_fd;
int async_fd;
int num_comp_vectors;
pthread_mutex_t mutex;
void *abi_compat;
struct ibv_xrc_ops *xrc_ops;
};
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