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Re: [RFC PATCH v2 3/5] exec/memattrs: Introduce MemTxAttrs::bus_perm fie
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From: |
Philippe Mathieu-Daudé |
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Subject: |
Re: [RFC PATCH v2 3/5] exec/memattrs: Introduce MemTxAttrs::bus_perm field |
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Date: |
Wed, 15 Dec 2021 18:14:20 +0100 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.3.0 |
On 8/23/21 21:04, David Hildenbrand wrote:
> On 23.08.21 20:41, Peter Xu wrote:
>> On Mon, Aug 23, 2021 at 06:41:55PM +0200, Philippe Mathieu-Daudé wrote:
>>> +/* Permission to restrict bus memory accesses. See
>>> MemTxAttrs::bus_perm */
>>> +enum {
>>> + MEMTXPERM_UNSPECIFIED = 0,
>>> + MEMTXPERM_UNRESTRICTED = 1,
>>> + MEMTXPERM_RAM_DEVICE = 2,
>>> +};
>>
>> Is there a difference between UNSPECIFIED and UNRESTRICTED?
>>
>> If no, should we merge them?
>>
>
> I'd assume MEMTXPERM_UNSPECIFIED has to be treated like
> MEMTXPERM_UNRESTRICTED, so I'd also think we should just squash them.
For now they are treated the same way, but ideally we should
explicitly classify bus accesses and remove the MEMTXPERM_UNSPECIFIED.
While we can use the same definition with comments, I think having
different definitions ease maintainance (thinking of git-grep), but
if we know we will never classify/convert the devices, then indeed
having MEMTXPERM_UNSPECIFIED is pointless and confusing.