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From: Julien Grall <julien.grall@arm.com>
To: "Edgar E. Iglesias" <edgar.iglesias@xilinx.com>
Cc: "Edgar E. Iglesias" <edgar.iglesias@gmail.com>,
	sstabellini@kernel.org, xen-devel@lists.xen.org
Subject: Re: [RFC for-4.8 v2 6/7] xen/device-tree: Add an mmio-sram bus
Date: Wed, 8 Jun 2016 09:52:57 +0100	[thread overview]
Message-ID: <75693d46-e30f-a0ea-632f-c2602e4748f2@arm.com> (raw)
In-Reply-To: <20160608002114.GB25740@toto>

Hi Edgar,

On 08/06/2016 01:21, Edgar E. Iglesias wrote:
> On Mon, Jun 06, 2016 at 07:05:20PM +0100, Julien Grall wrote:
>> Hi Edgar,
>>
>> On 03/06/16 14:29, Edgar E. Iglesias wrote:
>>> From: "Edgar E. Iglesias" <edgar.iglesias@xilinx.com>
>>>
>>> Add an mmio-sram bus that prevents sram sub areas from
>>> being re-mapped. These sub-areas describe allocations and
>>> not mappings.
>>
>> mmio-sram is not a bus and the region below should point to a valid physical
>> address.
>>
>> So why do you want that?
>
> Hi,
>
> Yes, I briefly mentioned this in the cover letter. It's a hack
> to avoid the mapping of sub allocations. The regions under mmio-sram
> point to valid addresses but they point into the same space that
> the outer mmio-sram node maps in. They also don't need to be page
> aligned. AFAICT, Xen should ignore these sub-regions allthough I
> think things work anyway (at least with my dts).

Sorry I haven't fully read the cover letter. I agree that going through 
those sub-regions are pointless because it already mapped by the parent.

However, it is harmless as they should be part of the parent MMIO. It 
also makes the code simpler.

>
> Maybe I should just drop this until we have a real problem or
> come up with a nicer way of dealing with this.

Sounds good to me.

Regards,

-- 
Julien Grall

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  reply	other threads:[~2016-06-08  8:52 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-03 13:29 [RFC for-4.8 v2 0/7] xen/arm: Add support for mapping mmio-sram nodes into dom0 Edgar E. Iglesias
2016-06-03 13:29 ` [RFC for-4.8 v2 1/7] xen/arm: Add MATTR_MEM_NC for normal non-cacheable memory Edgar E. Iglesias
2016-06-06 17:23   ` Julien Grall
2016-06-07 20:34     ` Edgar E. Iglesias
2016-06-03 13:29 ` [RFC for-4.8 v2 2/7] xen/arm: Rename and generalize un/map_regions_rw_cache Edgar E. Iglesias
2016-06-06 17:55   ` Julien Grall
2016-06-07 20:55     ` Edgar E. Iglesias
2016-06-03 13:29 ` [RFC for-4.8 v2 3/7] xen/device-tree: Add __DT_MATCH macros without braces Edgar E. Iglesias
2016-06-06 17:36   ` Julien Grall
2016-06-03 13:29 ` [RFC for-4.8 v2 4/7] xen/device-tree: Make dt_match_node match props Edgar E. Iglesias
2016-06-06 17:39   ` Julien Grall
2016-06-07 20:43     ` Edgar E. Iglesias
2016-06-08  8:44       ` Julien Grall
2016-06-09 16:04         ` Edgar E. Iglesias
2016-06-09 16:23           ` Julien Grall
2016-06-09 16:30             ` Edgar E. Iglesias
2016-06-03 13:29 ` [RFC for-4.8 v2 5/7] xen/arm: domain_build: Plumb for different mapping attributes Edgar E. Iglesias
2016-06-06 18:00   ` Julien Grall
2016-06-03 13:29 ` [RFC for-4.8 v2 6/7] xen/device-tree: Add an mmio-sram bus Edgar E. Iglesias
2016-06-06 18:05   ` Julien Grall
2016-06-08  0:21     ` Edgar E. Iglesias
2016-06-08  8:52       ` Julien Grall [this message]
2016-06-03 13:29 ` [RFC for-4.8 v2 7/7] xen/arm: Map mmio-sram nodes as normal un-cached rwx memory Edgar E. Iglesias
2016-06-06 18:08   ` Julien Grall

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