NetBSD Problem Report #57835

From  Thu Jan 11 04:19:12 2024
Return-Path: <>
Received: from ( [])
	(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits))
	(Client CN "", Issuer " CA" (not verified))
	by (Postfix) with ESMTPS id 99F281A9238
	for <>; Thu, 11 Jan 2024 04:19:12 +0000 (UTC)
Message-Id: <>
Date: Thu, 11 Jan 2024 04:18:41 +0000 (UTC)
Subject: x86 bus_dmamap_load_raw allegedly fails to respect maxsegsz
X-Send-Pr-Version: www-1.0

>Number:         57835
>Category:       port-amd64
>Synopsis:       x86 bus_dmamap_load_raw allegedly fails to respect maxsegsz
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-amd64-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Jan 11 04:20:00 +0000 2024
>Originator:     Taylor R Campbell
>Release:        current
The NetBSD Gemdation
In i915_gem_stolen.c, I wrote this comment some years ago, presumably on the basis of some empirical drudgery:

	 * XXX x86 bus_dmamap_load_raw fails to respect the maxsegsz we
	 * pass to bus_dmamap_create, so we have to create page-sized
	 * segments to begin with.

I haven't looked recently at x86 bus_dmamap_load_raw, so I don't know if this is true or up-to-date.

We should either

(a) find the bug and fix it, or
(b) determine that x86 bus_dmamap_load_raw does respect maxsegsz after all and delete the comments and workarounds.
code inspection
Yes, please!

NetBSD Home
NetBSD PR Database Search

(Contact us) $NetBSD: query-full-pr,v 1.47 2022/09/11 19:34:41 kim Exp $
$NetBSD:,v 1.9 2014/08/02 14:16:04 spz Exp $
Copyright © 1994-2024 The NetBSD Foundation, Inc. ALL RIGHTS RESERVED.