From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BCE532AEE9 for ; Wed, 2 Apr 2025 17:09:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743613797; cv=none; b=dJbAkwiJkKoCSTod0gkuGUivtrpXFSHm6uF0jKN+rLI3S1dJRoGKKsnK4zABIQgZR4TeIWbDOF5aIBOGXOqmpNVpKePAi5VSJz8yYyWw7sLpECq01fdoOugO3pfcyYOTIwP3cAjFnw/LkCmuiYGHVX3kZfNi1KqAQarkXSv61X8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743613797; c=relaxed/simple; bh=HtHYDth0F/plQJwYGwda6+uF2zNn055yNiXJQVssDiY=; h=From:In-Reply-To:References:To:Cc:Subject:MIME-Version: Content-Type:Date:Message-ID; b=lsVp7vPP3UWtJpOdKLjbXYCmN9dhRt3HkHhYLkTPildO7EprMwc6r/TqobmPzVI3TcvsUC3WPbOKNsGOeBDDpjTNgmX9ZZVDxXcRQYObfEUUWok/uIl3sw9OfMGNosMiKhj7uzcgFwd6ZLEpv72gdRXrALvn/Czd0lNyWF4YeGk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=UrQ5Yp/Y; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="UrQ5Yp/Y" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1743613794; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=oINYtJWfQ9LgmLRorSFrUIUNiQBEOvE5PqodZADRXDU=; b=UrQ5Yp/Y3DvEM726yoOU+tP6vj6WL0qWvYb0A1wBsI3BmkkwOOBd/RWIbBuKyGsa49Xowy bM3HjC84D0KlgvNWBW0W9C8ktWiNUbLjiHoD3JanK6WkNtoa6i9zWA5evS51IBLPDvUj+Y iSNCWgBE/PIyjFW3ketZr5eeox7psJc= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-687-gh6G64WVM5evjoEEgdgazg-1; Wed, 02 Apr 2025 13:09:51 -0400 X-MC-Unique: gh6G64WVM5evjoEEgdgazg-1 X-Mimecast-MFC-AGG-ID: gh6G64WVM5evjoEEgdgazg_1743613790 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 3652318001E0; Wed, 2 Apr 2025 17:09:49 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.42.28.40]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 0E0753001D0E; Wed, 2 Apr 2025 17:09:46 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <7e1fc71c-2821-4294-833c-746c5fd7ee69@talpey.com> References: <7e1fc71c-2821-4294-833c-746c5fd7ee69@talpey.com> <78c910b0-3391-484e-aa44-42e2f9ff4637@talpey.com> <563557.1743526559@warthog.procyon.org.uk> <659109.1743536087@warthog.procyon.org.uk> To: Tom Talpey Cc: dhowells@redhat.com, Steve French , Stefan Metzmacher , Paulo Alcantara , Matthew Wilcox , linux-cifs@vger.kernel.org Subject: Re: cifs RDMA restrictions Precedence: bulk X-Mailing-List: linux-cifs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <803440.1743613785.1@warthog.procyon.org.uk> Date: Wed, 02 Apr 2025 18:09:45 +0100 Message-ID: <803441.1743613785@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Tom Talpey wrote: > > But, will the device handle that? And can the DMA API map a single buffer > > that big with the IOMMU? And does it need aligning to a larger pow-of-2 > > granule? > > Yes, maybe and no. > 1 - The device just expects a base and length, so size is not an issue. > 2 - The IOMMU is a platform question, if it's in use and the mapping > allows, it should work. > 3 - No specific alignment required. Is there a way to query the RDMA layer as to its limits? David