From: Christoph Hellwig <hch@lst.de>
To: Robin Murphy <robin.murphy@arm.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
iommu@lists.linux-foundation.org, will@kernel.org,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH] dma-mapping: remove CONFIG_DMA_REMAP
Date: Mon, 28 Feb 2022 12:04:38 +0100 [thread overview]
Message-ID: <20220228110438.GA10232@lst.de> (raw)
In-Reply-To: <4802e9fd-733f-3246-92f3-05f590e05d37@arm.com>
On Mon, Feb 28, 2022 at 10:32:54AM +0000, Robin Murphy wrote:
> Is it even possible to hit this case now? From a quick look, all the
> architectures defining HIGHMEM either have an explicit dependency on MMU or
> don't allow deselecting it anyway (plus I don't see how HIGHMEM && !MMU
> could work in general), so I'm pretty sure this whole chunk should go away
> now.
>
> With that (or if there *is* some subtle wacky case where PageHighmem() can
> actually return true for !MMU, a comment to remind us in future),
No, you're right - I don't think we can support highmem on !CONFIG_MMU.
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WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Christoph Hellwig <hch@lst.de>,
iommu@lists.linux-foundation.org, joro@8bytes.org,
will@kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] dma-mapping: remove CONFIG_DMA_REMAP
Date: Mon, 28 Feb 2022 12:04:38 +0100 [thread overview]
Message-ID: <20220228110438.GA10232@lst.de> (raw)
In-Reply-To: <4802e9fd-733f-3246-92f3-05f590e05d37@arm.com>
On Mon, Feb 28, 2022 at 10:32:54AM +0000, Robin Murphy wrote:
> Is it even possible to hit this case now? From a quick look, all the
> architectures defining HIGHMEM either have an explicit dependency on MMU or
> don't allow deselecting it anyway (plus I don't see how HIGHMEM && !MMU
> could work in general), so I'm pretty sure this whole chunk should go away
> now.
>
> With that (or if there *is* some subtle wacky case where PageHighmem() can
> actually return true for !MMU, a comment to remind us in future),
No, you're right - I don't think we can support highmem on !CONFIG_MMU.
next prev parent reply other threads:[~2022-02-28 11:04 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-27 14:35 [PATCH] dma-mapping: remove CONFIG_DMA_REMAP Christoph Hellwig
2022-02-27 14:35 ` Christoph Hellwig
2022-02-28 10:32 ` Robin Murphy
2022-02-28 10:32 ` Robin Murphy
2022-02-28 11:04 ` Christoph Hellwig [this message]
2022-02-28 11:04 ` Christoph Hellwig
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