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References: <20170429123707.16675-1-aik@ozlabs.ru>
	<20170502182550.5edb9565.cornelia.huck@de.ibm.com>
From: Alexey Kardashevskiy <aik@ozlabs.ru>
Message-ID: <e6d90400-3bcd-77c5-dbe6-24dc14d6bcd3@ozlabs.ru>
Date: Wed, 3 May 2017 11:25:16 +1000
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Subject: Re: [Qemu-devel] [PATCH qemu v5] memory/iommu: QOM'fy IOMMU
 MemoryRegion
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To: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: qemu-devel@nongnu.org, qemu-ppc@nongnu.org, David Gibson <david@gibson.dropbear.id.au>, Alex Williamson <alex.williamson@redhat.com>, Christian Borntraeger <borntraeger@de.ibm.com>, Paolo Bonzini <pbonzini@redhat.com>, Peter Xu <peterx@redhat.com>, =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= <f4bug@amsat.org>

On 03/05/17 02:25, Cornelia Huck wrote:
> On Sat, 29 Apr 2017 22:37:07 +1000
> Alexey Kardashevskiy <aik@ozlabs.ru> wrote:
> 
>> This defines new QOM object - IOMMUMemoryRegion - with MemoryRegion
>> as a parent.
>>
>> This moves IOMMU-related fields from MR to IOMMU MR. However to avoid
>> dymanic QOM casting in fast path (address_space_translate, etc),
>> this adds an @is_iommu boolean flag to MR and provides new helper to
>> do simple cast to IOMMU MR - memory_region_get_iommu. The flag
>> is set in the instance init callback. This defines
>> memory_region_is_iommu as memory_region_get_iommu()!=NULL.
>>
>> This switches MemoryRegion to IOMMUMemoryRegion in most places except
>> the ones where MemoryRegion may be an alias.
>>
>> This defines memory_region_init_iommu_type() to allow creating
>> IOMMUMemoryRegion subclasses. In order to support custom QOM type,
>> this splits memory_region_init() to object_initialize() +
>> memory_region_do_init.
>>
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> 
>>  /**
>> + * memory_region_init_iommu_type: Initialize a memory region of a custom type
>> + * that translates addresses
>> + *
>> + * An IOMMU region translates addresses and forwards accesses to a target
>> + * memory region.
>> + *
>> + * @typename: QOM class name
>> + * @iommumr: the #IOMMUMemoryRegion to be initialized
> 
> <bikeshed>
> I find "iommumr" terribly hard to read. Maybe iommu_mr is better? (Lots
> of times in this patch.)
> </bikeshed>

Terribly? Really? :) Seriously, since linux uses underscores in typenames,
I kind of developed resistance to underscores in variable names which look
like typenames (even though c allows using same token for a type and a
variable). May be just "iommu"? I need one more vote for "iommu" vs.
"iommumr" vs. "iommu_mr" to respin v6 :)


> 
> The s390 parts look fine.
> 


-- 
Alexey