Re: [Qemu-devel] [PATCH 1/2] Keep track of ISA ports ISA device is using in qdev.

[Markus Armbruster]

Gleb Natapov <address@hidden> writes:

> On Mon, Oct 25, 2010 at 05:06:51PM +0200, Markus Armbruster wrote:
>> Gleb Natapov <address@hidden> writes:
>> 
>> > Prevent two devices from claiming the same io port.
>> 
>> Really?
>> 
>> Your new check for double-claim is in the new isa_init_ioport(), which
>> is for ISADevice only.  Thus, only qdevified ISA devices can opt for
>> this protection, by calling isa_init_ioport().  It doesn't protect from
>> devices who don't or can't opt in, such as PCI devices.
>> 
> I didn't claim different. This obviously works only for ISA qdev
> devices.

I read "Prevent two devices from claiming the same io port" as such.

>> Anyway, we already check for double-claim in
>> register_ioport_{read,write}().  The check has issues --- hw_error() is
>> wrong there for hot plug.  But it's where the check should be, isn't it?
> You don't like double-claim checking? Forget about it (all 3 lines
> of code). The real point of the patch is to have ISA resources used
> by devices to be stored in common place (ISADevice) which allows
> get_dev_path() to be implemented.

We already track I/O port use, in ioport.c.  I don't like that
duplicated.  Even less so if the dupe catches fewer double-claims than
the original.

Perhaps your new function should wrap around register_ioport_*() instead
of supplementing it.