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From: "Sven Peter" <>
To: "Arnd Bergmann" <>, "Christoph Hellwig" <>
Subject: Re: [asahilinux:nvme/dev 13/17] drivers/nvme/host/pci.c:2249:2-3: Unneeded semicolon
Date: Mon, 09 Aug 2021 22:11:19 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Mon, Aug 9, 2021, at 17:53, Arnd Bergmann wrote:
> On Mon, Aug 9, 2021 at 4:29 PM Christoph Hellwig <> wrote:
> > Also can one of you look how PRPs are actually used by MacOS?  Given
> > that this device always seems to be behind a IOMMU creating one entry
> > per page seems rather weird given that the apple_nvmmu_tcb structure
> > already contains the full length.  Maybe it actually ignores all but
> > the first PRP?
> I'll leave this up to Sven to answer. He also wrote the iommu driver,
> so he probably has a good idea of what is going on here already.
>       Arnd

Not yet, but figuring out how this NVMe-IOMMU works in detail was
already on my TODO list :-)

Some background - the M1 has at least four different IOMMU-like
HW blocks:
DART (for which I wrote a driver and where I'd actually know what's going
on in detail), SART (simple DMA address filter required by the NVMe
co-processor for non-nvme transactions), this weird NVMe IOMMU (that
also seems to be somehow related to disk encryption) and GART for their GPU.


Linux-nvme mailing list

  reply	other threads:[~2021-08-09 20:12 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <>
     [not found] ` <>
2021-08-09 10:02   ` [asahilinux:nvme/dev 13/17] drivers/nvme/host/pci.c:2249:2-3: Unneeded semicolon Arnd Bergmann
2021-08-09 14:29     ` Christoph Hellwig
2021-08-09 15:53       ` Arnd Bergmann
2021-08-09 20:11         ` Sven Peter [this message]
2021-08-18  6:26           ` Sven Peter

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