Re: [PATCH rdma-next 10/11] RDMA/erdma: Add the ABI definitions

[Leon Romanovsky <leon@kernel.org>]

On Fri, Dec 24, 2021 at 03:54:18PM +0800, Yanjun Zhu wrote:
> 在 2021/12/24 14:04, Leon Romanovsky 写道:
> > On Fri, Dec 24, 2021 at 06:55:41AM +0800, Yanjun Zhu wrote:
> > > 在 2021/12/24 2:45, Leon Romanovsky 写道:
> > > > On Thu, Dec 23, 2021 at 11:46:03PM +0800, Yanjun Zhu wrote:
> > > > > 在 2021/12/21 10:48, Cheng Xu 写道:
> > > > > > Signed-off-by: Cheng Xu <chengyou@linux.alibaba.com>
> > > > > > ---
> > > > > >     include/uapi/rdma/erdma-abi.h | 49 +++++++++++++++++++++++++++++++++++
> > > > > >     1 file changed, 49 insertions(+)
> > > > > >     create mode 100644 include/uapi/rdma/erdma-abi.h
> > > > > > 
> > > > > > diff --git a/include/uapi/rdma/erdma-abi.h b/include/uapi/rdma/erdma-abi.h
> > > > > > new file mode 100644
> > > > > > index 000000000000..6bcba10c1e41
> > > > > > --- /dev/null
> > > > > > +++ b/include/uapi/rdma/erdma-abi.h
> > > > > > @@ -0,0 +1,49 @@
> > > > > > +/* SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR Linux-OpenIB) */
> > > > > > +/*
> > > > > > + * Copyright (c) 2020-2021, Alibaba Group.
> > > > > > + */
> > > > > > +
> > > > > > +#ifndef __ERDMA_USER_H__
> > > > > > +#define __ERDMA_USER_H__
> > > > > > +
> > > > > > +#include <linux/types.h>
> > > > > > +
> > > > > > +#define ERDMA_ABI_VERSION       1
> > > > > 
> > > > > ERDMA_ABI_VERSION should be 2？
> > > > 
> > > > Why?
> > > > 
> > > > This field is for rdma-core and we don't have erdma provider in that
> > > > library yet. It always starts from 1 for new drivers.
> > > Please check this link:
> > > http://mail.spinics.net/lists/linux-rdma/msg63012.html
> > 
> > OK, I still don't understand why.
> 
> 
> Perhaps 32 bit machines require ABI version 2 which guarentees the user and
> kernel use the same ABI.

Nope, it is not.

> 
> Zhu Yanjun
> 
> > 
> > RXE case is different, because rdma-core already had broken RXE
> > implementation, so this is why the version was incremented.
> > 
> > > 
> > > Jason mentioned in this link:
> > > 
> > > "
> > > /*
> > >   * For 64 bit machines ABI version 1 and 2 are the same. Otherwise 32
> > >   * bit machines require ABI version 2 which guarentees the user and
> > >   * kernel use the same ABI.
> > >   */
> > > "
> > > 
> > > Zhu Yanjun
> > > > 
> > > > Thanks
> > > 
>