Re: [Qemu-devel] [PATCH v4 2/2] hw/integratorcp: Simplify flash remap code

["Andreas Färber" <afaerber@suse.de>]

Am 08.01.2012 12:16, schrieb Avi Kivity:
> On 01/07/2012 06:09 PM, Peter Maydell wrote:
>> On 7 January 2012 04:40, Andreas Färber <afaerber@suse.de> wrote:
>>> I noticed you're dropping a comment about tlb_flush(). Is that because
>>> it was dead code, or does the Memory API take care of it for us?
>>> (I assume the former because memory_region_set_enabled() does not take a
>>> CPUState* to operate on.)
>>
>> Arranging for a tlb_flush if needed has to be the Memory API's
>> problem, because everything that uses the memory API to rearrange
>> the view of the address space has exactly the same requirement that
>> anything else in QEMU has to be told it may need to redo any caching
>> data structure it has set up. In particular, this doesn't apply just
>> for a single CPUState* -- in a multicore system every CPU has to be
>> made aware that the world has changed, not just the one which
>> happened to do the store to the "remap the flash" register.
>> Also the memory API is the only thing that knows whether the region
>> was already enabled (ie this is a no-op), whether some other region
>> is overlapping so in fact it makes no difference whether we enable
>> or disable this one, etc etc).
>>
>> So basically I dropped that line because it was a bit of commented
>> out code with a ??? marker appended, and the device layer is the
>> wrong place to be trying to solve the issue it was gesturing at.
>>
> 
> Correct, and the memory core will flush the tlb, so all is well.

Hm, I had grep'ed for tlb_flush in memory.* without a hit...
I would've assumed to find tlb_flush_all() somewhere.

Andreas

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