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Date: Thu, 05 Jan 2012 09:17:34 +0100
From: Stefan Weil <sw@weilnetz.de>
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Subject: Re: [Qemu-devel] [PATCH] Rename target_phys_addr_t to Phys
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Avi Kivity <avi@redhat.com>, qemu-devel@nongnu.org

Am 05.01.2012 01:24, schrieb Peter Maydell:
> On 5 January 2012 00:16, Anthony Liguori <anthony@codemonkey.ws> wrote:
>> On 01/04/2012 05:33 PM, Peter Maydell wrote:
>>> A lot of the usage of target_phys_addr_t in hw/ is actually not
>>> handling addresses at all, but merely offsets into device IO regions
>>> (ie as parameters to device read/write functions)...
>>
>> Exactly, which is why using target_phys_addr_t (and subsequently building
>> the device twice) doesn't make a lot of sense.
>
> So should we have a hw_offset type for this? That would cut out a lot
> of the noise and let us find out how much code in hw/ is actually
> using physaddrs...
>
> -- PMM

Hardware offsets are hardware: you can count the address lines
or get the values from the vendor's manual (you cannot count when
serial protocolsare used). A 32 bit PCI card will take 32 bit
offsets (or smaller), even when itis used in a 64 bit host.

It should be possible to model that in QEMU, too. uint8_t,
uint16_t, uint32_t and uint64_t are good enough to describe
the typical offset ranges of any hardware.

Cheers,
Stefan Weil