qemu-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] Memory API: handling unassigned physical memory


From: Blue Swirl
Subject: Re: [Qemu-devel] Memory API: handling unassigned physical memory
Date: Sun, 6 May 2012 08:45:49 +0000

On Wed, May 2, 2012 at 3:15 PM, Bob Breuer <address@hidden> wrote:
> On 5/1/2012 1:48 PM, Mark Cave-Ayland wrote:
>> On 01/05/12 07:57, Blue Swirl wrote:
>>
>>>> Therefore I can't change it to my (modified) sbus_mmio_map() function
>>>> because it would break other non-SPARC platforms, and AIUI there is
>>>> nothing
>>>> in the memory API that allows me to move a subregion to a different
>>>> MemoryRegion parent, even if I can get a reference to it with
>>>> sysbus_mmio_get_region() after the sysbus_mmio_map() call - or have I
>>>> misunderstood something?
>>>
>>> Sysbus is used as a generic class for motherboard devices, there is an
>>> assumption that there is no higher level bus. What we need here is a
>>> full blown bus. The translations and mappigs between bus addresses and
>>> motherboard addresses should be done in a Sysbus to SBus bridge
>>> device, just like PCI host bridges do.
>>
>> Since SBus is mapped directly to physical addresses, is this mapping not
>> just 1:1? Or does it make sense to re-work all the offsets of the
>> various peripherals to be from the base address of the first slot?
>
> It would be nice to have the device offsets be relative to the slot.
> User-pluggable sbus devices should be possible.

Yes, currently all devices are fixed but for example display adapter
should be pluggable and only on-board devices should be fixed.

> I've just pushed an update of a dbri sbus device model to github (
> https://github.com/breuerr/qemu/commits/dbri-pre2 ).  This device was
> built-in to at least the SS-20, but also available as an sbus add-in
> card (SunLink ISDN).  There's an fcode rom so it can be probed by OBP,
> and if we could get something like "-device SUNW,,DBRIe,slot=1" to work,
> then a user could add it to most of the sun4m machine models.

Nice work.

>
> Bob



reply via email to

[Prev in Thread] Current Thread [Next in Thread]