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From: Christoph Hellwig <hch@infradead.org>
To: Vladimir Kondratiev <vladimir.kondratiev@mobileye.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org
Subject: Re: [PATCH] riscv: make ZONE_DMA32 optional
Date: Fri, 20 Sep 2024 07:04:06 -0700	[thread overview]
Message-ID: <Zu2A1l_cX36sOVcB@infradead.org> (raw)
In-Reply-To: <20240827113611.537302-1-vladimir.kondratiev@mobileye.com>

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.


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  parent reply	other threads:[~2024-09-20 14:04 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-08-27 11:36 [PATCH] riscv: make ZONE_DMA32 optional Vladimir Kondratiev
2024-08-27 23:10 ` Drew Fustini
2024-09-20  8:58   ` Palmer Dabbelt
2024-09-20 13:18     ` Drew Fustini
2024-09-23  9:46       ` Ben Dooks
2024-09-20 14:04 ` Christoph Hellwig [this message]
2024-09-22 10:06   ` Vladimir Kondratiev
2024-09-24  6:39     ` Christoph Hellwig
2024-09-30  9:55 ` Alexandre Ghiti
2024-10-06 10:44   ` Vladimir Kondratiev
2024-10-06 10:55     ` [PATCH v1] " Vladimir Kondratiev
2024-10-06 22:58       ` Drew Fustini
2024-10-07  5:41       ` Christoph Hellwig
2024-10-07  6:17         ` Vladimir Kondratiev
2024-10-07  6:22           ` Christoph Hellwig
2024-10-07 11:39             ` Nick Kossifidis
2024-10-07 13:03             ` Vladimir Kondratiev
2024-10-07 12:17     ` [PATCH] " Ben Dooks

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