Re: [Qemu-devel] [RFC 0/4] Adding -cdrom, -hd[abcd] and -drive file=... to Q35

[John Snow <jsnow@redhat.com>]

On 08/19/2014 12:12 PM, Dr. David Alan Gilbert wrote:
> * John Snow (jsnow@redhat.com) wrote:
>
> <snip>
>
>> The changes appear to work well, but where I'd like some feedback
>> is what should happen if people do something like:
>>
>> qemu -M q35 -drive if=ide,file=fedora.qcow2
>>
>> The code as presented here is not going to look for or attempt to
>> connect IDE devices, because it is now looking for /AHCI/ devices.
>
> What happens if you try it - does it just silently ignore that -drive?
> The ideal would be for something to moan about unused drives so people
> realise why it's broken; but I seem to remember form a previous discussion
> it's hard to do on all platforms.

With this patch, piix would continue to ignore AHCI and Q35 would ignore 
IDE. piix and Q35 both can be corrected to look for either/or IDE/AHCI 
and whine if you mix them. Q35 and piix both could be made to throw an 
error if you specify drives that the board doesn't pick up (AHCI in the 
case of piix if you have not specified that device, legacy IDE in the 
case of Q35 until we add legacy mode support and the user specifies that 
mode.)

I suggested to Markus in a different reply that I could add a little 
flag to the drive list to help identify if any drives don't get picked 
up at board spin-up time... But it sounds like it might not be quite so 
simple.

I will wait to add error handling modes until there is perhaps some 
consensus that the basic approach here is desirable.

-- 
—js