On Mon, Feb 26, 2018 at 11:57:42AM -0700, Jason Gunthorpe wrote:
> On Mon, Feb 26, 2018 at 03:02:21PM +0200, Leon Romanovsky wrote:
> > From: Yishai Hadas <yishaih@xxxxxxxxxxxx>
> >
> > This patch explicitly aligns 'mlx4_uverbs_ex_query_device_resp' layout
> > to u64 and use the correct response's length when copying the data to
> > the user area.
> >
> > The uAPI should be u64 aligned, currently on 64 bit systems this is done
> > implicitly as of the next u64 field in the rss_caps structure.
> >
> > Legacy user space 32 bit system application in any case is broken with
> > 64 bit system kernel before this change.
> >
> > A matching change will be done in the user area for future use also on
> > 32 bit systems.
> >
> > In addition, we move the structure to the uAPI file where it's expected
> > to be from day one.
> >
> > Fixes: 09d208b258a2 ("IB/mlx4: Add report for RSS capabilities by vendor channel")
> > Reviewed-by: Mark Bloch <markb@xxxxxxxxxxxx>
> > Signed-off-by: Yishai Hadas <yishaih@xxxxxxxxxxxx>
> > Signed-off-by: Leon Romanovsky <leon@xxxxxxxxxx>
> > drivers/infiniband/hw/mlx4/main.c | 5 +++--
> > drivers/infiniband/hw/mlx4/mlx4_ib.h | 14 --------------
> > include/uapi/rdma/mlx4-abi.h | 16 ++++++++++++++++
> > 3 files changed, 19 insertions(+), 16 deletions(-)
>
> So I am unhappy that we keep finding these 32/64 compat bugs. I sent a
> RFC patch for rxe as well.
>
> Any change like this breaks any previously working 32/32
> configuration.
>
> So what is the position here?
Official position,
Mellanox doesn't support 32/32 configurations for mlx4/mlx5 devices.
>
> The 32/32 API is 'not used' but the 32/64 is being used, so we break
> one to fix the other?
>
> How do we justify this to Linus?
Exactly as you are supposed to justify rename of "reserved" fields to
something meaningful. The change is in mlx4-abi.h and all users of this
file are known.
Thanks
>
> Jason
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