From: Julien Grall <julien.grall@arm.com>
To: Stefano Stabellini <sstabellini@kernel.org>
Cc: edgar.iglesias@xilinx.com, Steve Capper <Steve.Capper@arm.com>,
Andre Przywara <andre.przywara@arm.com>,
xen-devel@lists.xen.org, Shannon Zhao <shannon.zhao@linaro.org>,
"Edgar E. Iglesias" <edgar.iglesias@gmail.com>,
Wei Chen <Wei.Chen@linaro.org>
Subject: Re: [RFC for-4.8 0/6] xen/arm: Add support for mapping mmio-sram nodes into dom0
Date: Wed, 25 May 2016 10:52:07 +0100 [thread overview]
Message-ID: <574575C7.1090002@arm.com> (raw)
In-Reply-To: <alpine.DEB.2.10.1605251032350.2958@sstabellini-ThinkPad-X260>
Hi Stefano,
On 25/05/16 10:43, Stefano Stabellini wrote:
>> For SRAM it would be normal memory uncached (?) when the property
>> "no-memory-wc" is not present, else TBD.
>>
>> I suspect we would have to relax more MMIOs in the future. Rather than
>> providing a function to map, the code is very similar except the memory
>> attribute, I suggest to provide a list of compatible with the memory attribute
>> to use.
>>
>> All the children node would inherit the memory attribute of the parent.
>>
>> What do you think?
>
> That would work for device tree, but we still need to rely on the
> hypercall for ACPI systems.
>
> Given that it is not easy to add an additional parameter to
> XENMEM_add_to_physmap_range, I think we'll have to provide a new
> hypercall to allow setting attributes other than the Xen default. That
> could be done in Xen 4.8 and Linux >= 4.9.
There is no need to introduce a new hypercall. The
XENMEM_add_to_physmap_batch contains an unused field ('foreign_id', to
be renamed) for mapping device MMIOs (see Jan's mail [1]).
XENMEM_add_to_physmap will always map with the default memory attribute
(Device_nGnRnE) and if the kernel want to use another memory attribute,
it will have to use XENMEM_add_to_physmap_batch.
With the plan suggested in [2], there are no modifications required in
Linux for the moment.
Regards,
[1]
http://lists.xenproject.org/archives/html/xen-devel/2016-05/msg02341.html
[2]
http://lists.xenproject.org/archives/html/xen-devel/2016-05/msg02347.html
--
Julien Grall
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next prev parent reply other threads:[~2016-05-25 9:52 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-20 15:51 [RFC for-4.8 0/6] xen/arm: Add support for mapping mmio-sram nodes into dom0 Edgar E. Iglesias
2016-05-20 15:51 ` [RFC for-4.8 1/6] xen/arm: Add device_get_desc() Edgar E. Iglesias
2016-05-20 15:51 ` [RFC for-4.8 2/6] xen/arm: Add an optional map function to the device descriptor Edgar E. Iglesias
2016-05-20 15:51 ` [RFC for-4.8 3/6] xen/arm: Add a DEVICE_MEMORY class Edgar E. Iglesias
2016-05-20 15:51 ` [RFC for-4.8 4/6] xen/arm: Add helper functions to map RWX memory regions Edgar E. Iglesias
2016-05-23 15:36 ` Julien Grall
2016-05-24 14:14 ` Edgar E. Iglesias
2016-05-20 15:51 ` [RFC for-4.8 5/6] xen/arm: Add an mmio-sram device Edgar E. Iglesias
2016-05-20 15:51 ` [RFC for-4.8 6/6] xen/arm: Avoid multiple dev class lookups in handle_node Edgar E. Iglesias
2016-05-23 10:29 ` [RFC for-4.8 0/6] xen/arm: Add support for mapping mmio-sram nodes into dom0 Julien Grall
2016-05-23 11:56 ` Edgar E. Iglesias
2016-05-23 13:02 ` Julien Grall
2016-05-23 14:02 ` Edgar E. Iglesias
2016-05-23 15:13 ` Julien Grall
2016-05-23 15:42 ` Edgar E. Iglesias
2016-05-24 19:44 ` Julien Grall
2016-05-25 9:43 ` Stefano Stabellini
2016-05-25 9:52 ` Julien Grall [this message]
2016-05-25 10:00 ` Stefano Stabellini
2016-05-25 10:35 ` Edgar E. Iglesias
2016-05-25 13:29 ` Edgar E. Iglesias
2016-05-25 14:24 ` Julien Grall
2016-06-03 13:10 ` Edgar E. Iglesias
2016-05-25 9:31 ` Stefano Stabellini
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