From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f51.google.com (mail-wm1-f51.google.com [209.85.128.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4922A26F2BF for ; Fri, 22 May 2026 08:31:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.51 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779438715; cv=none; b=nkYmcUWtFTMSjtmrnRUsZViwjjupmi3ERen9etk3XR8zXZYE6Zyy13iLog7/rBGXI9Hv7wCUdfTmOa9eWN+yptYJl1fUOJx7p4FKyrHUCdB+HtRw7oR3unUJIQrEOBXz203AVG5uPX3ZfhXNqrvC1RzWmm0CHQGP5Jswe/qlIX8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779438715; c=relaxed/simple; bh=EEqkT27TlId4h3beUOLCoSv9cHFPJwmJ+6ESFzXgDKI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=jjdzSlYdtEHPnzGPp8N8uWWmuGTImZaqyW80Etx2+EU5bVDUi4dGr5cAhUOdWEvna0qHoFVWxGwpFgELR0e5bFs8K7hpUy9pyZJV+GKF9WGm2+px6OOJUya9I7g0sxgHgkix0+h6dYgY/6WKs6/nN3fvHEsmvqDJ7PtcuCqw1G8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=resnulli.us; spf=none smtp.mailfrom=resnulli.us; dkim=pass (2048-bit key) header.d=resnulli-us.20251104.gappssmtp.com header.i=@resnulli-us.20251104.gappssmtp.com header.b=QWg1Gavd; arc=none smtp.client-ip=209.85.128.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=resnulli.us Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=resnulli.us Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=resnulli-us.20251104.gappssmtp.com header.i=@resnulli-us.20251104.gappssmtp.com header.b="QWg1Gavd" Received: by mail-wm1-f51.google.com with SMTP id 5b1f17b1804b1-48e82c23840so56705915e9.3 for ; Fri, 22 May 2026 01:31:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=resnulli-us.20251104.gappssmtp.com; s=20251104; t=1779438708; x=1780043508; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=5L+TbgpqpAMywBwsF4TYhq+71zfTDBHT9Bwfrcc2e1w=; b=QWg1Gavd1iqgBKM+eTgaUVrs1bs55Du2SSkFzFRHepd2fj8fGvQ235aXjH9W10l/D1 y+kqhlKBeFZI1Kypd+AK7uVQKw4OqvQhcUY51ZYS5uTMkdbyYorz2aJfWgW/vHnSSgrJ RB/n5RMWusnJ2NeCaDT5XA7mghyzFDz3PsVhi2xeA51gFng3MU5YZTMPR1pYapDUMGPs +u36t/hcIxsdzdWfx1Yrsp5IRBunbXz2zimBNmdFURhmGn+gXht6KuO9bU1nSr9vM099 vnaaWpNLBiztP2lrTXxGuhlKCm5xKIWTIGx1A6iMq1sM+y8oj/PFYX9Sk8VSKAILlrU5 FLvQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779438708; x=1780043508; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=5L+TbgpqpAMywBwsF4TYhq+71zfTDBHT9Bwfrcc2e1w=; b=fN4gjL03m1Gt6K4FJ2IoxtNwK0gokWv4Jwwkdc2OaT/V6zGFxd3+BQ8cH5AWFn5LK4 YBTnBxFB28TeV2QLCgaFTtEB01JwlQ5YYg3wkTtPFS+SBv1VX0/DT+JdSq60eXxp7wCz jUJxkB14fPUlrr6+hXcOmolz0hS5zvXdP/YrW++QE2KsoaR7MDzQPTy54HDVo7clFRIF 8c95q7PTXmOD+M8pjGhFmh3nO4ZZWxLojAZ0I1kvz9UH1Bn/MQtISXccbugLAdE23UTP zO30+L2zcdHipSdik9C99xhJCqx/vKM6ImjUOn9ylmoQzfnTOGhkqrFYWchXdpZ2pU1U 8jow== X-Gm-Message-State: AOJu0YxgVkipbS3qw23zveUNFPgDSCRMSP0doLxofaZzXpX6gyhlQJ7Y nMQt67cQg2M2LurM1kFOcxOi8XGlyS/1NpBn8B/QDLaVRGrjFFude3XsfhPXzp9DoTM= X-Gm-Gg: Acq92OFtyPFT3UEYEv7WKvN13cyXBvS5fIbHRmmsZMx7UBN6+fCT4gE8LBJWiw+xYp4 gUiw+bUxNQOyLJeY1y5whwKLRDuFvPo+NJXUqOw9DytEC/VbdRQCY+5Yan846GtasG4ASPcEmTa aWyNhOybecZn6Wx85nZ6STXDllAJXs9pLZYcFEJCouC3EpdB6f3GBtmM3pIuhRjIdG2+CkLYHPM RtcoJK+ksJNLNN7iEtqHwydxIZiJysq2cKQpte9cUihQja1nESE0VH5y+a63ZlQeMITvzhnGZN9 ko7VXgF/C/L/YlaJW91A6dfiwJkiKDSfQz44dt4z2TYHNHD0Z1Sfgnjmg2U0jO+iW9Z7T/jKqeo e7gkPAHKLxg1Y456bdy5et/XGjwOjRvUgixepprlpd37ZSWOzOWEyaXFp7xqBv2KPR9sjd9ktn6 yO90XPgEwWUYSLRJ8gYR+ZrOylmcBtWHJv20BqelVZ00I= X-Received: by 2002:a05:600c:8484:b0:490:3b87:be0e with SMTP id 5b1f17b1804b1-490428e3362mr30797615e9.29.1779438708254; Fri, 22 May 2026 01:31:48 -0700 (PDT) Received: from localhost ([140.209.217.212]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4904526ca50sm25643615e9.2.2026.05.22.01.31.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 22 May 2026 01:31:47 -0700 (PDT) Date: Fri, 22 May 2026 10:31:43 +0200 From: Jiri Pirko To: Jason Gunthorpe 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 Message-ID: References: <20260520101129.899464-1-jiri@resnulli.us> <20260520101129.899464-4-jiri@resnulli.us> <20260520160844.GW7702@ziepe.ca> Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260520160844.GW7702@ziepe.ca> Wed, May 20, 2026 at 06:08:44PM +0200, jgg@ziepe.ca wrote: >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.. No problem. Will replace reverved[2] by "flags" and "optional_flag". > >I also want to think about how we can discover if the kernel supports >this new path from userspace.. This is problematic. This is up to the driver if it implements specific ATTR (may be generic or driver specific) or not. Not sure how to do this. Per driver list of supported ATTRs? Idk. Ideas? One way or another, this could be easily a follow-up.