Re: [Qemu-block] [Qemu-devel] [PATCH v2 8/8] hw: Drop superfluous special checks for orphaned -drive

[Markus Armbruster]

John Snow <address@hidden> writes:

> On 01/26/2017 10:09 AM, Markus Armbruster wrote:
>> We've traditionally rejected orphans here and there, but not
>> systematically.  For instance, the sun4m machines have an onboard SCSI
>> HBA (bus=0), and have always rejected bus>0.  Other machines with an
>> onboard SCSI HBA don't.
>> 
>> Commit a66c9dc made all orphans trigger a warning, and the previous
>> commit turned this into an error.  The checks "here and there" are now
>> redundant.  Drop them.
>> 
>> Note that the one in mips_jazz.c was wrong: it rejected bus > MAX_FD,
>> but MAX_FD is the number of floppy drives per bus.
>> 
>> Error messages change from
>> 
>>     $ qemu-system-x86_64 -drive if=ide,bus=2
>>     qemu-system-x86_64: Too many IDE buses defined (3 > 2)
>>     $ qemu-system-mips64 -M magnum,accel=qtest -drive if=floppy,bus=2,id=fd1
>>     qemu: too many floppy drives
>>     $ qemu-system-sparc -M LX -drive if=scsi,bus=1
>>     qemu: too many SCSI bus
>> 
>> to
>> 
>>     $ qemu-system-x86_64 -drive if=ide,bus=2
>>     qemu-system-x86_64: -drive if=ide,bus=2: machine type does not support 
>> this drive
>>     $ qemu-system-mips64 -M magnum,accel=qtest -drive if=floppy,bus=2,id=fd1
>>     qemu-system-mips64: -drive if=floppy,bus=2,id=fd1: machine type does not 
>> support this drive
>>     $ qemu-system-sparc -M LX -drive if=scsi,bus=1
>>     qemu-system-sparc: -drive if=scsi,bus=1: machine type does not support 
>> this drive
>> 
>
> Hm, that's a lot less helpful, isn't it? Can we augment with hints?

The message itself may be less specific, but it now comes with a precise
location.  Personally, I'd even find

    qemu-system-sparc: -drive if=scsi,bus=1: *mumble* *mumble*

more helpful than

    qemu: too many SCSI bus

because the former tells me *which* of the options is bad.  We tend to
have lots and lots of them.

The deleted special case errors cover only a minority of "orphan"
-drive.  If these cases need improvement, then so will the general case.
If you can come up with a hint that makes the general case message more
useful, I'm more than happy to squash it into PATCH 6.