> On Oct 14, 2016, at 9:50 AM, Andriy Gapon <a...@freebsd.org> wrote:
> Could you please open a bugzilla issue for the bug?
Sure, will do. I was unsure of the effectiveness of that, because I filed a
much more serious report about a different issue a couple of weeks ago and have
seen no activity or even acknowledgement.
> The src change is described as "Expand SMBUS API ...", but in fact it also
> _changed_ the existing ioctls. And both binary compatibility and programming
> compatibility were broken because of how struct smbcmd was changed.
> In FreeBSD we try to not do that without a very strong reason, but alas.
> And, as you report, the change was not done entirely correctly.
I was also surprised, but it wasn’t really a big deal, and the new structure
might be slightly easier to use. There have been other similar things in 11.0,
like __mq_oshandle() disappearing, and more .so files needing to be added to
our embedded system, so all things considered, it’s been reasonably smooth
moving from 10.3 to 11.0.
> I see several possibilities now.
> Option 1. Change the documentation to reflect the actual behavior.
> In this case data.rdata will remain unusable and unused. No interface
> Option 2. Redefine SMB_READB, SMB_READW and SMB_PCALL ioctls using _IOWR, so
> that data.rdata could be returned from kernel. This seems like a proper fix,
> but it is another binary level incompatibility.
> Option 3. Use a horrible hack to discover a userland address of smbcmd and
> explicitly copyout to data.rdata. No interface incompatibilities, but it will
> be a horrible hack. Besides, not sure how feasible it is.
> Option 4. Revert smb ioctl changes to what they used to be before r281985.
> Personally, I would prefer this approach. But now that the new interface is
> 11.0, it means another interface change just like Option 2.
> I would like to hear other developers' opinions about this situation.
Our opinion doesn’t count for much, but I like 2 or 4. Option 1 would
essentially obviate the entire purpose of changing the structure. Option 2
basically finishes the job and makes it work properly. Option 3 is, as you
say, unappealing. I have no problem with Option 4, obviously we can change our
code back to the old way, but assuming there was a good reason for this change
in the first place, Option 2 seems more logical.
But whatever y’all decide is fine with us, we’ll just change code to match at
the appropriate time.
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