From: Will Deacon <will@kernel.org>
To: Robin Murphy <robin.murphy@arm.com>
Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
Joerg Roedel <joro@8bytes.org>,
Bjorn Helgaas <bhelgaas@google.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
saravanak@google.com
Subject: Re: [PATCH 0/7] iommu: Permit modular builds of ARM SMMU[v3] drivers
Date: Wed, 30 Oct 2019 15:54:45 +0000 [thread overview]
Message-ID: <20191030155444.GC19096@willie-the-truck> (raw)
In-Reply-To: <6e457227-ca06-2998-4ffa-a58ab171ce32@arm.com>
Hi Robin,
On Wed, Oct 30, 2019 at 03:35:55PM +0000, Robin Murphy wrote:
> On 30/10/2019 14:51, Will Deacon wrote:
> > As part of the work to enable a "Generic Kernel Image" across multiple
> > Android devices, there is a need to seperate shared, core kernel code
> > from modular driver code that may not be needed by all SoCs. This means
> > building IOMMU drivers as modules.
> >
> > It turns out that most of the groundwork has already been done to enable
> > the ARM SMMU drivers to be 'tristate' options in drivers/iommu/Kconfig;
> > with a few symbols exported from the IOMMU/PCI core, everything builds
> > nicely out of the box. The one exception is support for the legacy SMMU
> > DT binding, which is not in widespread use and has never worked with
> > modules, so we can simply remove that when building as a module rather
> > than try to paper over it with even more hacks.
> >
> > Obviously you need to be careful about using IOMMU drivers as modules,
> > since late loading of the driver for an IOMMU serving active DMA masters
> > is going to end badly in many cases. On Android, we're using device links
> > to ensure that the IOMMU probes first.
>
> Out of curiosity, which device links are those? Clearly not the RPM links
> created by the IOMMU drivers themselves... Is this some special Android
> magic, or is there actually a chance of replacing all the
> of_iommu_configure() machinery with something more generic?
I'll admit that I haven't used them personally yet, but I'm referring to
this series from Saravana [CC'd]:
https://lore.kernel.org/linux-acpi/20190904211126.47518-1-saravanak@google.com/
which is currently sitting in linux-next now that we're upstreaming the
"special Android magic" ;)
Will
next prev parent reply other threads:[~2019-10-30 16:00 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-30 14:51 [PATCH 0/7] iommu: Permit modular builds of ARM SMMU[v3] drivers Will Deacon
2019-10-30 14:51 ` [PATCH 1/7] drivers/iommu: Export core IOMMU API symbols to permit modular drivers Will Deacon
2019-10-30 14:51 ` [PATCH 2/7] iommu/of: Request ACS from the PCI core when configuring IOMMU linkage Will Deacon
2019-10-30 14:51 ` [PATCH 3/7] PCI: Export pci_ats_disabled() as a GPL symbol to modules Will Deacon
2019-10-30 20:30 ` Bjorn Helgaas
2019-10-30 14:51 ` [PATCH 4/7] Revert "iommu/arm-smmu: Make arm-smmu-v3 explicitly non-modular" Will Deacon
2019-10-30 14:51 ` [PATCH 5/7] iommu/arm-smmu-v3: Allow building as a module Will Deacon
2019-10-30 19:31 ` Joerg Roedel
2019-10-31 15:42 ` Will Deacon
2019-11-04 19:15 ` Jean-Philippe Brucker
2019-11-08 14:54 ` Will Deacon
2019-11-05 12:15 ` Joerg Roedel
2019-11-08 11:03 ` Will Deacon
2019-10-30 14:51 ` [PATCH 6/7] Revert "iommu/arm-smmu: Make arm-smmu explicitly non-modular" Will Deacon
2019-10-30 23:09 ` Jordan Crouse
2019-10-31 12:03 ` Will Deacon
2019-10-31 15:32 ` Jordan Crouse
2019-10-30 14:51 ` [PATCH 7/7] iommu/arm-smmu: Allow building as a module Will Deacon
2019-10-30 15:22 ` Rob Herring
2019-10-30 15:26 ` Will Deacon
2019-10-30 15:33 ` Robin Murphy
2019-11-04 19:34 ` Isaac J. Manjarres
2019-11-07 12:48 ` Will Deacon
2019-10-30 15:35 ` [PATCH 0/7] iommu: Permit modular builds of ARM SMMU[v3] drivers Robin Murphy
2019-10-30 15:54 ` Will Deacon [this message]
2019-10-31 0:57 ` Saravana Kannan
2019-10-31 19:37 ` Jean-Philippe Brucker
2019-10-31 23:34 ` Saravana Kannan
2019-11-01 10:27 ` John Garry
2019-11-01 21:13 ` Saravana Kannan
2019-11-04 12:16 ` John Garry
2019-11-04 13:29 ` Robin Murphy
2019-11-07 6:11 ` Saravana Kannan
2019-11-07 9:13 ` Jean-Philippe Brucker
2019-11-07 6:02 ` Saravana Kannan
2019-11-01 11:41 ` Jean-Philippe Brucker
2019-11-01 12:28 ` Lorenzo Pieralisi
2019-11-01 21:26 ` Saravana Kannan
2019-11-04 11:43 ` Lorenzo Pieralisi
2019-11-07 5:55 ` Saravana Kannan
2019-11-01 17:21 ` Will Deacon
2019-11-04 7:54 ` Jean-Philippe Brucker
2019-11-07 6:16 ` Saravana Kannan
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