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Re: [Qemu-devel] vga optmization
From: |
Glauber Costa |
Subject: |
Re: [Qemu-devel] vga optmization |
Date: |
Mon, 3 Nov 2008 16:14:46 -0200 |
On Mon, Nov 3, 2008 at 4:03 PM, Blue Swirl <address@hidden> wrote:
> On 11/3/08, Glauber Costa <address@hidden> wrote:
>> Hi guys,
>>
>> this is a port of current kvm vga memory optimization to our new
>> infrastructure proposed by anthony. It's goal is to use as few
>> kvm specific hooks as possible. In fact, the only one I'm relying
>> on is enabling/disabling of logging. The rest, is pretty much general.
>>
>> We map the linear frame buffer area as RAM, and then use dirty tracking
>> to decide whether or not to update it. To be consistent with qemu,
>> this version, differently from upstream kvm, tracks memory based on its
>> physical address, represented by vram_offset, instead of vram_ptr, or
>> any other construct.
>>
>> Let me know what you think
>
> The patch does not apply, because of the kvm files. What patches do I
> need to apply first? I'd like to see how does the optimization apply
> to TCX.
Yes, you are missing kvm patches some time ago, which he plans to merge.
> This also may mean that some of my comments below can be invalid.
>
>> +void set_vram_mapping(target_phys_addr_t begin, target_phys_addr_t end,
>> ram_addr_t target)
>
> No "static"?
thanks, will update.
>
>> +{
>> + /* align begin and end address */
>> + begin = begin & TARGET_PAGE_MASK;
>> + end = begin + VGA_RAM_SIZE;
>> + end = (end + TARGET_PAGE_SIZE -1 ) & TARGET_PAGE_MASK;
>
> This will fail if "end" is at the last page of the memory.
How so? I don't think it's possible for the addr 0xsomething0001 to be
valid, but 0x(something+1)000 to be not.
>
>> + uint32_t vga_io_memory; \
>
> cpu_register_io_memory() returns an "int".
can it possibly be negative?
that said, of course I can change it for consistency, but I'd like to
understand it more
thanks
--
Glauber Costa.
"Free as in Freedom"
http://glommer.net
"The less confident you are, the more serious you have to act."