Re: [Qemu-devel] memory: Why subpage is introduced?

[Zhi Yong Wu]

anyway, thanks.

On Thu, Dec 22, 2011 at 8:38 PM, Avi Kivity <address@hidden> wrote:
> On 12/22/2011 01:24 PM, Zhi Yong Wu wrote:
>> >
>> >> 2.) How to render MemoryRegion into one disjoint flatrange list? That
>> >> rendering function is a bit difficult to understand. Can anyone simply
>> >> explain it?
>> >
>> > What exactly don't you understand?
>> 1.) e.g. some fields such as offset_in_region, terminates, offset in
>> MemoryRegion struct. What are separately their meanings?
>
> Well, read the code, it's not that complicated.  Afterwards you can add
> documentation based on your findings.
>
>> 2.)  render_memory_region(), how does it render one MemoryRegion into
>> the global view flatview? Can you simply explain this function's
>> algorithm logic?
>
> Again, what can I say that the code doesn't?  It recursively descends
> the hierarchy and finds out which region goes where.
>
> Also read docs/memory.txt
>
>>
>> >
>> >>
>> >> 3.) What are separately the meanings of these flags? such as
>> >> IO_MEM_RAM, IO_MEM_ROM, IO_MEM_UNASSIGNED, IO_MEM_*, IO_MEM_ROMD, and
>> >> IO_MEM_SUBPAGE.
>> >
>> > RAM = RAM
>> > ROM = ROM
>> > UNASSIGNED = nothing handles this range
>> > ROMD = ROM when read, device (i.e. callbacks) when written
>> > SUBPAGE = dispatch using the lower address bits to obtain final I/O 
>> > handler.
>> thanks.
>>
>> By the way, if you are available, can you simply explain what is the
>> relationship among them and how they work together? such as
>> MemoryRegion, RamBlock, PhysPageDesc, and MemorySlot.
>>
>
> Sorry, it's a long and complicated story that is changing now.  You'll
> have to educate yourself mostly.
>
> --
> error compiling committee.c: too many arguments to function
>



-- 
Regards,

Zhi Yong Wu