Re: [Qemu-devel] Seabios dislikes -M isapc

[Anthony Liguori <anthony@codemonkey.ws>]

On 02/09/2010 05:25 PM, Aurelien Jarno wrote:
> On Wed, Feb 10, 2010 at 01:41:01AM +0300, malc wrote:
>    
>> On Tue, 9 Feb 2010, Natalia Portillo wrote:
>>
>>      
>>> Xenix is currently working (when copied from real hardware).
>>> As well Interactive UNIX and some other non-DOS from 8086 and 286 era.
>>>
>>> I'm not really sure that operating systems (specially the 8086 ones that do
>>> mmu functions in software) will be happy with the PCI bus present.
>>>
>>> Same for first 386 operating systems (OS/2 2, UNIX, Xenix, so on).
>>>        
>> News to me that OS/2 worked.. I don't quite remember which version
>> someone (you?) asked me to try on IRC a few years back, but it definitely
>> didn't work.
>>
>>      
> I have got OS/2 warp working under QEMU a few years ago. I couldn't give
> more details though, I just remember it was working nicely.
>    

The problem with isapc is that it uses a different chipset (or rather, 
doesn't use a PCI chipset).  I think the current thinking with 
target-i386 config files is that while you should be able to customize 
the system, some of the core bits would always be there.  For instance, 
the PCI chipset, the APIC, etc.  These things are very tied to a platform.

Firmware is really hard to implement if you have to deal with supporting 
multiple chipsets.

Also, if we don't have a workload that actually needs isapc, that 
suggests that there's no real way to test that isapc doesn't have 
non-ISA things creep into it.

Given that, I'm inclined to suggest that we mark isapc as deprecated, 
give people some time to comment on it, and then provided that we still 
don't think it's necessary, change isapc to simply use isa devices while 
still using a PCI chipset.

Regards,

Anthony Liguori