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Date: Tue, 29 Sep 2009 09:19:45 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [Qemu-devel] Re: [PATCHv2] qemu: target library, use it in msix
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To: Avi Kivity <avi@redhat.com>
Cc: Blue Swirl <blauwirbel@gmail.com>, qemu-devel@nongnu.org

On Sun, Sep 27, 2009 at 04:26:33PM +0200, Avi Kivity wrote:
> On 09/27/2009 04:21 PM, Michael S. Tsirkin wrote:
>>
>>> How can the caller (except in your special case) know if it has a
>>> quantity that will fit in 32 bits?
>>>      
>> It's actually not unusual for devices to limit addressing to 32 bit, whatever
>> the bus supports.  For example, the value might come from a 32 bit pci
>> bar, even on a 64 bit system this will get values 0 to 4G.
>>    
>
> What if the caller is a device that doesn't intentionally cripple itself?

That will need a 64 bit version, even if target is 32 bit.

> -- 
> Do not meddle in the internals of kernels, for they are subtle and quick to panic.