[openib-general] Re: Questions about libibat, ib_uat, and ib_a

[Hal Rosenstock]

On Wed, 2005-11-02 at 01:02, Pradeep Satyanarayana wrote:
> openib-general-bounces at openib.org wrote on 10/18/2005 03:40:47 PM:
> 
> > 
> > 
> > 
> > 
> > On Mon, 2005-10-18 at 10:07, Kevin Reilly wrote:
> > >On Mon, 2005-10-17 at 10:07, Hal Rosenstock wrote:
> > >> > Should this code work, because it seems that out_dev is a
> kernel
> > >> > address (platform: PPC64) which cannot accessed  by a userspace
> > >> > program. Via GDB I can see that rt has the following content:
> > >> >
> > >> > The address is rt->out_dev = 0xc0000000cffaa800 which looks
> like a
> > >> > kernel address.
> > >>
> > >> Yes, this is a bug which has been previously pointed out on the
> list and
> > >> not fixed.
> > >
> 
> Can some one point me to the previous discussions on this list (search
> did not yield any results)? 

There were various posts from Heiko J Schick <SCHICKHJ at de.ibm.com> on
10/17 and subsequent ones from Kevin.

> The problem is because of a copy_to_user (in uat.c) between struct
> ib_at_ib_route
> which are different between user and kernel space causing this crash. 
> What was the rationale of putting a pointer to struct ibv_device in
> the user space version of
> ib_at_ib_route? The out_dev field in user space is not really used as
> far as I could see.
> 
> > >The fix for this involves an ABI change: it should return the GID
> of the
> > >outgoing IB device.
> > >
> 
> Would a simple solution like adding a device_name field to both the
> ib_at_ib_route structures
> be acceptable? The out_dev field could be used as a "reserved" field
> in user space and not be used.
> That should not break anything as far as I can see.

Ideally, the current out_dev field should be removed and all consumers
should be converted over to the new structures/interfaces.

Guess the question also is whether people want this by name, GID, or
both ?

-- Hal

> > >-- Hal
> 
> Pradeep
> pradeep at us.ibm.com
> 
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