From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B6EE7C78849 for ; Fri, 20 Sep 2024 14:04:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=FDUzvVpPrsQ3sKgsFy5XO5yQzZGPz73td2pWf5b/yr4=; b=tm1Yjrd3kUM6qr uvRaaaeMbFmmGKbypkbMFj1yShONb7QnCKrlFrANkOmehKyrNvp8stsDsmgAl/YBiQUAZo/iUbq8l kNfrVAwIIjlmz+HI4Yt0kiH4UkRI1l98C442dkKWyv7lJNs3FkpgInRzRWEBghg5wRuCHo56l14dG JM/vRBb2eglUqdBKLisApWWPP99zsM5g771vIovtkdJHgoj/W0gKFlvQkCDVNU5S50vLRd23xZonF b8uf1SxQZwjcblZVtUIshATCza/QaaQ/Q6SlgiY02B7H1H8hXkLJ91AXKOttbDF1sYRSOEWTxJRrU BfcNZ8kM5DrOkhJeeskw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1sreEy-0000000CK7d-2Gpb; Fri, 20 Sep 2024 14:04:08 +0000 Received: from hch by bombadil.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1sreEw-0000000CK7O-25DY; Fri, 20 Sep 2024 14:04:06 +0000 Date: Fri, 20 Sep 2024 07:04:06 -0700 From: Christoph Hellwig To: Vladimir Kondratiev Cc: Paul Walmsley , Palmer Dabbelt , Albert Ou , Andrew Morton , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] riscv: make ZONE_DMA32 optional Message-ID: References: <20240827113611.537302-1-vladimir.kondratiev@mobileye.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240827113611.537302-1-vladimir.kondratiev@mobileye.com> X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Tue, Aug 27, 2024 at 02:36:11PM +0300, Vladimir Kondratiev wrote: > It is not necessary any RISCV platform has ZONE_DMA32. That is an odd statement. The point of ZONE_DMA32 is to make sure that drivers can always allocate 32-bit DMAable memory, and without ZONE_DMA32 that is very hard to provide unless you always have an IOMMU. > Example - if platform has no DRAM in [0..4G] region, > it will report failure like below each boot. ZONE_DMA32 is supposed to contain the 32-bit dma addressable memory, not 32-bit physical. Take a look at the changes that just went into Linus' tree for that. _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv