Linux RDMA and InfiniBand development
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From: Jason Gunthorpe <jgg@ziepe.ca>
To: Jiri Pirko <jiri@resnulli.us>
Cc: linux-rdma@vger.kernel.org, leon@kernel.org, edwards@nvidia.com,
	kees@kernel.org, parav@nvidia.com, mbloch@nvidia.com,
	yishaih@nvidia.com, lirongqing@baidu.com,
	huangjunxian6@hisilicon.com, liuy22@mails.tsinghua.edu.cn,
	jmoroni@google.com
Subject: Re: [PATCH rdma-next v6 03/15] RDMA/core: Introduce generic buffer descriptor infrastructure for umem
Date: Wed, 20 May 2026 13:08:44 -0300	[thread overview]
Message-ID: <20260520160844.GW7702@ziepe.ca> (raw)
In-Reply-To: <20260520101129.899464-4-jiri@resnulli.us>

On Wed, May 20, 2026 at 12:11:17PM +0200, Jiri Pirko wrote:
> +int uverbs_attr_get_buffer_desc(const struct uverbs_attr_bundle *attrs,
> +				u16 attr_id,
> +				struct ib_uverbs_buffer_desc *desc)
> +{
> +	int ret;
> +
> +	ret = uverbs_copy_from(desc, attrs, attr_id);
> +	if (ret)
> +		return ret;
> +	if (desc->reserved[0] || desc->reserved[1])
> +		return -EINVAL;

I'd like to carve out some space for optional kernel ignored flags
here.

Basically a flags field that kernel just ignores. If userspace
requests a flag through this field that the kernel does not support it
ignores the request and does nothing. 

Then a seperate flags that the kernel does enforce every set bit is
understood.

We've not included this a few times in the past and were sad about
it..

I also want to think about how we can discover if the kernel supports
this new path from userspace..

Jason

  reply	other threads:[~2026-05-20 16:08 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-20 10:11 [PATCH rdma-next v6 00/15] RDMA: Introduce generic buffer descriptor infrastructure for umem Jiri Pirko
2026-05-20 10:11 ` [PATCH rdma-next v6 01/15] RDMA/umem: Rename ib_umem_get() to ib_umem_get_va() Jiri Pirko
2026-05-20 10:11 ` [PATCH rdma-next v6 02/15] RDMA/umem: Split ib_umem_get_va() into a thin wrapper around __ib_umem_get_va() Jiri Pirko
2026-05-20 10:11 ` [PATCH rdma-next v6 03/15] RDMA/core: Introduce generic buffer descriptor infrastructure for umem Jiri Pirko
2026-05-20 16:08   ` Jason Gunthorpe [this message]
2026-05-22  8:31     ` Jiri Pirko
2026-05-22 11:57       ` Jason Gunthorpe
2026-05-20 10:11 ` [PATCH rdma-next v6 04/15] RDMA/umem: Route ib_umem_get_va() through ib_umem_get_attr_or_va() Jiri Pirko
2026-05-20 10:11 ` [PATCH rdma-next v6 05/15] RDMA/uverbs: Push out CQ buffer umem processing into a helper Jiri Pirko
2026-05-20 10:11 ` [PATCH rdma-next v6 06/15] RDMA/uverbs: Add CQ buffer UMEM attribute and driver helpers Jiri Pirko
2026-05-20 10:11 ` [PATCH rdma-next v6 07/15] RDMA/efa: Use ib_umem_get_cq_buf() for user CQ buffer Jiri Pirko
2026-05-20 10:11 ` [PATCH rdma-next v6 08/15] RDMA/mlx5: Use ib_umem_get_cq_buf_or_va() " Jiri Pirko
2026-05-20 10:11 ` [PATCH rdma-next v6 09/15] RDMA/bnxt_re: " Jiri Pirko
2026-05-20 10:11 ` [PATCH rdma-next v6 10/15] RDMA/mlx4: Use ib_umem_get_cq_buf() " Jiri Pirko
2026-05-20 10:11 ` [PATCH rdma-next v6 11/15] RDMA/uverbs: Remove legacy umem field from struct ib_cq Jiri Pirko
2026-05-20 10:11 ` [PATCH rdma-next v6 12/15] RDMA/uverbs: Use UMEM attributes for QP creation Jiri Pirko
2026-05-20 10:11 ` [PATCH rdma-next v6 13/15] RDMA/mlx5: Use UMEM attributes for QP buffers in create_qp Jiri Pirko
2026-05-20 10:11 ` [PATCH rdma-next v6 14/15] RDMA/mlx5: Use UMEM attribute for CQ doorbell record Jiri Pirko
2026-05-20 10:11 ` [PATCH rdma-next v6 15/15] RDMA/mlx5: Use UMEM attribute for QP " Jiri Pirko

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