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Re: [Qemu-devel] [PATCH] pci: add standard bridge device

From: Avi Kivity
Subject: Re: [Qemu-devel] [PATCH] pci: add standard bridge device
Date: Sun, 04 Sep 2011 17:36:56 +0300
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:6.0) Gecko/20110816 Thunderbird/6.0

On 09/04/2011 05:21 PM, Michael S. Tsirkin wrote:
>  >
>  >+static pcibus_t pci_bridge_get_size(const PCIDevice *bridge, uint8_t type)
>  >+{
>  >+    return pci_bridge_get_limit(bridge, type)>=
>  >+        pci_bridge_get_base(bridge, type) ?
>  >+        pci_bridge_get_limit(bridge, type) -
>  >+        pci_bridge_get_base(bridge, type)  + 1 : 0;
>  >+}
>  Correct

To make sure: 0 size is ok?


>  but unreadable.

variables will make it clearer.

base = pci_bridge_get_base(bridge, type);
limit = pci_bridge_get_limit(bridge, type);
return limit>= bridge ? limit - base + 1 : 0;

So long as we're nitpicking, limit + 1 - base.

>   Doesn't work for limit == 2^64-1, is this a
>  possible value?

You mean when base == 0?  Yes, but what can I do?
This seems to be an API limitation of the memory API:
memory_region_init(sec_bus->address_space_mem, "pci_pridge_pci", INT64_MAX);
and the same for aliases: max size seems to be INT64_MAX,
the last byte isn't covered.


The only way to fix this would be to pass first/last instead
of offset/size. Too late for such an API change?

Way too late. And also won't work, since often the offset is determined by one party and the size by another.

VGA I/O addresses (including ISA aliases address - AD[15::10] are not
AD[9::0] = 3B0h through 3BBh and 3C0h through 3DFh

These "not decoded" bits mean you need to instantiate tons of aliases to implement correctly.

I plan to add core support for that eventually.

error compiling committee.c: too many arguments to function

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