Using XRC between kernel and user space.

Using XRC between kernel and user space.

[Shlomo Pongratz]

Hi,

I wonder how a kernel "program" and a user space one can communicate 
using XRC.
A example for such an application is iSER kernel initiator connected to 
tgtd target that runs in user space.
The XRC domain in the kernel is created with "struct ib_xrcd 
*ib_alloc_xrcd(struct ib_device *device)" while in the user space it is 
created with "static inline struct ibv_xrcd * ibv_open_xrcd(struct 
ibv_context *context, struct ibv_xrcd_init_attr *xrcd_init_attr)".
When looking in "xrc_pingpong.c" example we can see that the attribute 
has some file descriptor of some file ("/tmp/xrc_domain").
So how a kernel "program" on one machine can communicate with a user 
space program on another one?
The XRC annex (page 9) sates that all QP should belong to the same XRC 
domain.

S.P.

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Re: Using XRC between kernel and user space.

[Shlomo Pongratz]

On 4/4/2013 8:44 PM, Shlomo Pongratz wrote:
> Hi,
>
> I wonder how a kernel "program" and a user space one can communicate 
> using XRC.
> A example for such an application is iSER kernel initiator connected 
> to tgtd target that runs in user space.
> The XRC domain in the kernel is created with "struct ib_xrcd 
> *ib_alloc_xrcd(struct ib_device *device)" while in the user space it 
> is created with "static inline struct ibv_xrcd * ibv_open_xrcd(struct 
> ibv_context *context, struct ibv_xrcd_init_attr *xrcd_init_attr)".
> When looking in "xrc_pingpong.c" example we can see that the attribute 
> has some file descriptor of some file ("/tmp/xrc_domain").
> So how a kernel "program" on one machine can communicate with a user 
> space program on another one?
> The XRC annex (page 9) sates that all QP should belong to the same XRC 
> domain.
>
> S.P.
>

Sorry, I misinterpreted the annex.
I thank Roland for clarifying this to me.

S.P.


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