From: Joerg Roedel <jroedel@suse.de>
To: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>, Andy Lutomirski <luto@kernel.org>,
Cornelia Huck <cornelia.huck@de.ibm.com>,
Sebastian Ott <sebott@linux.vnet.ibm.com>,
Paolo Bonzini <pbonzini@redhat.com>,
benh@kernel.crashing.org, KVM <kvm@vger.kernel.org>,
dwmw2@infradead.org, Martin Schwidefsky <schwidefsky@de.ibm.com>,
linux-s390 <linux-s390@vger.kernel.org>
Subject: Re: [PATCH 1/4] Provide simple noop dma ops
Date: Fri, 30 Oct 2015 23:45:58 +0900 [thread overview]
Message-ID: <20151030144558.GA2704@suse.de> (raw)
In-Reply-To: <563368DC.3080606@de.ibm.com>
On Fri, Oct 30, 2015 at 01:55:56PM +0100, Christian Borntraeger wrote:
> It not trivial without understanding the dma mask details. Do I read
> the x86 implementation right, that it limits the dma to 32 bit? Then
> we cannot collapse both implementations. Or maybe we can hide this in
> dma_capable. Dont know
No, DMA is not limited to 32bit on x86. Each device has its own
dma_mask, and the requested address+size is checked against it. The
DMA_BIT_MASK(32) check is only to there to print a warning when a 32bit
capable device trys to access memory above 4GB.
Joerg
next prev parent reply other threads:[~2015-10-30 14:46 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-27 22:48 [PATCH/RFC 0/4] dma ops and virtio Christian Borntraeger
2015-10-27 22:48 ` [PATCH 1/4] Provide simple noop dma ops Christian Borntraeger
2015-10-28 0:41 ` Joerg Roedel
2015-10-30 12:55 ` Christian Borntraeger
2015-10-30 14:45 ` Joerg Roedel [this message]
2015-10-27 22:48 ` [PATCH 2/4] alpha: use common " Christian Borntraeger
2015-10-27 22:48 ` [PATCH 3/4] s390/dma: Allow per device " Christian Borntraeger
2015-10-27 22:48 ` [PATCH 4/4] s390/virtio: use noop " Christian Borntraeger
2015-10-28 0:43 ` Joerg Roedel
2015-10-28 8:44 ` Cornelia Huck
2015-10-30 12:56 ` Christian Borntraeger
2015-10-30 12:17 ` Cornelia Huck
2015-10-30 12:26 ` Christian Borntraeger
2015-10-30 12:32 ` Cornelia Huck
2015-10-28 0:45 ` [PATCH/RFC 0/4] dma ops and virtio Joerg Roedel
2015-10-28 22:22 ` Andy Lutomirski
2015-10-29 0:04 ` Christian Borntraeger
2015-10-29 22:50 ` Andy Lutomirski
2015-10-30 8:25 ` Cornelia Huck
2015-10-30 20:33 ` Andy Lutomirski
2015-11-02 11:16 ` Cornelia Huck
2015-11-02 20:23 ` Andy Lutomirski
2015-11-03 8:14 ` Christian Borntraeger
2015-11-03 17:54 ` Andy Lutomirski
2015-11-03 17:59 ` Cornelia Huck
2015-11-03 18:45 ` Andy Lutomirski
2015-11-04 14:29 ` Cornelia Huck
2015-11-04 17:52 ` Cornelia Huck
2015-11-04 18:14 ` Andy Lutomirski
2015-11-05 8:11 ` Cornelia Huck
2015-11-12 7:56 ` Cornelia Huck
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