linux-parisc.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Russell King - ARM Linux <linux@armlinux.org.uk>
To: David Miller <davem@davemloft.net>
Cc: torvalds@linux-foundation.org, hch@lst.de,
	linux-arch@vger.kernel.org, linux-ia64@vger.kernel.org,
	linux-parisc@vger.kernel.org, robin.murphy@arm.com,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	iommu@lists.linux-foundation.org, linux-alpha@vger.kernel.org,
	xen-devel@lists.xenproject.org, dwmw2@infradead.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: remove the ->mapping_error method from dma_map_ops V2
Date: Wed, 28 Nov 2018 19:47:09 +0000	[thread overview]
Message-ID: <20181128194708.GP30658@n2100.armlinux.org.uk> (raw)
In-Reply-To: <20181128.112717.149234960284639699.davem@davemloft.net>

On Wed, Nov 28, 2018 at 11:27:17AM -0800, David Miller wrote:
> From: Linus Torvalds <torvalds@linux-foundation.org>
> Date: Wed, 28 Nov 2018 10:00:06 -0800
> 
> > Not all memory is accessible even to the kernel. If you have memory
> > that shows up in the last page of phys_addr_t, you just mark it
> > reserved at boot-time.
> 
> It's not the physical memory at the end that needs to be reserved.
> 
> It's the IOMMU mapping arena.

True, if and only if you have an IOMMU.

Where there isn't an IOMMU, then we'd have to reserve every page that
that translates to a bus address in the top 4K of dma_addr_t on any
bus in the system - that means knowing early in the kernel
initialisation about all buses in the system so we can detect and
reserve these pages.

I don't think that's trivial to do.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up
According to speedtest.net: 11.9Mbps down 500kbps up

  reply	other threads:[~2018-11-28 19:47 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-22 14:02 remove the ->mapping_error method from dma_map_ops V2 Christoph Hellwig
2018-11-22 14:02 ` [PATCH 01/24] dma-direct: Make DIRECT_MAPPING_ERROR viable for SWIOTLB Christoph Hellwig
2018-11-22 14:02 ` [PATCH 02/24] swiotlb: Skip cache maintenance on map error Christoph Hellwig
2018-11-22 14:02 ` [PATCH 03/24] dma-mapping: provide a generic DMA_MAPPING_ERROR Christoph Hellwig
2018-11-22 14:03 ` [PATCH 04/24] dma-direct: remove the mapping_error dma_map_ops method Christoph Hellwig
2018-11-22 14:03 ` [PATCH 05/24] arm: " Christoph Hellwig
2018-11-22 14:03 ` [PATCH 06/24] powerpc/iommu: " Christoph Hellwig
2018-11-22 14:03 ` [PATCH 07/24] mips/jazz: " Christoph Hellwig
2018-11-22 14:03 ` [PATCH 08/24] s390: " Christoph Hellwig
2018-11-22 14:03 ` [PATCH 09/24] sparc: " Christoph Hellwig
2018-11-22 14:03 ` [PATCH 10/24] parisc/ccio: " Christoph Hellwig
2018-11-22 14:03 ` [PATCH 11/24] parisc/sba_iommu: " Christoph Hellwig
2018-11-22 14:03 ` [PATCH 12/24] arm64: remove the dummy_dma_ops mapping_error method Christoph Hellwig
2018-11-22 14:03 ` [PATCH 13/24] alpha: remove the mapping_error dma_map_ops method Christoph Hellwig
2018-11-22 14:03 ` [PATCH 14/24] ia64/sba_iommu: improve internal map_page users Christoph Hellwig
2018-11-22 14:03 ` [PATCH 15/24] ia64/sba_iommu: remove the mapping_error dma_map_ops method Christoph Hellwig
2018-11-22 14:03 ` [PATCH 16/24] ia64/sn: " Christoph Hellwig
2018-11-22 14:03 ` [PATCH 17/24] x86/amd_gart: " Christoph Hellwig
2018-11-22 14:03 ` [PATCH 18/24] x86/calgary: " Christoph Hellwig
2018-11-22 14:03 ` [PATCH 19/24] iommu: " Christoph Hellwig
2018-11-22 14:03 ` [PATCH 20/24] iommu/intel: small map_page cleanup Christoph Hellwig
2018-11-22 14:03 ` [PATCH 21/24] iommu/vt-d: remove the mapping_error dma_map_ops method Christoph Hellwig
2018-11-22 14:03 ` [PATCH 22/24] iommu/dma-iommu: " Christoph Hellwig
2018-11-22 14:03 ` [PATCH 23/24] xen-swiotlb: " Christoph Hellwig
2018-11-22 14:03 ` [PATCH 24/24] dma-mapping: " Christoph Hellwig
2018-11-22 16:50 ` remove the ->mapping_error method from dma_map_ops V2 Linus Torvalds
2018-11-22 17:07   ` Russell King - ARM Linux
2018-11-22 17:09     ` Linus Torvalds
2018-11-22 17:14       ` Russell King - ARM Linux
2018-11-22 17:52       ` Robin Murphy
2018-11-22 17:55         ` Linus Torvalds
2018-11-22 18:05           ` Russell King - ARM Linux
2018-11-23  6:57             ` Christoph Hellwig
2018-11-23  6:55           ` Christoph Hellwig
2018-11-28  7:41             ` Christoph Hellwig
2018-11-28 16:47               ` Linus Torvalds
2018-11-28 17:45                 ` Russell King - ARM Linux
2018-11-28 18:00                   ` Linus Torvalds
2018-11-28 18:08                     ` Russell King - ARM Linux
2018-11-28 19:23                       ` Russell King - ARM Linux
     [not found]                       ` <CAHk-=whcbiSxSUprsKjVPEdN5-+o8WnTGiKxEV-+HbKNDs=iNA@mail.gmail.com>
2018-11-28 19:31                         ` Russell King - ARM Linux
2018-11-29 16:23                         ` Christoph Hellwig
2018-11-29 17:44                           ` Linus Torvalds
2018-11-29 18:31                             ` Christoph Hellwig
2018-11-29 18:53                               ` Linus Torvalds
2018-11-29 18:55                                 ` Christoph Hellwig
2018-11-28 19:27                     ` David Miller
2018-11-28 19:47                       ` Russell King - ARM Linux [this message]
2018-11-28 23:01                         ` Shuah Khan
2018-11-23 10:49         ` Joerg Roedel
2018-11-23 11:01           ` Russell King - ARM Linux
2018-11-23 13:03             ` Joerg Roedel
2018-11-23 13:20               ` Russell King - ARM Linux

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20181128194708.GP30658@n2100.armlinux.org.uk \
    --to=linux@armlinux.org.uk \
    --cc=davem@davemloft.net \
    --cc=dwmw2@infradead.org \
    --cc=hch@lst.de \
    --cc=iommu@lists.linux-foundation.org \
    --cc=linux-alpha@vger.kernel.org \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-ia64@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-parisc@vger.kernel.org \
    --cc=robin.murphy@arm.com \
    --cc=torvalds@linux-foundation.org \
    --cc=x86@kernel.org \
    --cc=xen-devel@lists.xenproject.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).