Re: [Qemu-devel] [PATCHv2] parallel: Allow to disable CONFIG_PARALLEL

[Markus Armbruster <armbru@redhat.com>]

Paolo Bonzini <pbonzini@redhat.com> writes:

> On 11/05/2015 11:36, Miroslav Rezanina wrote:
>>> > This patch will make "-parallel" a nop.  The right thing to do is to
>>> > fail startup whenever -parallel is passed and CONFIG_PARALLEL is disabled.
>>> > 
>> This was original behavior before 07dc788. Intention of this patch is to
>> make qemu buildable with CONFIG_PARALLEL disabled.
>
> Understood, but in the meanwhile Markus wrote commit 4bc6a3e (parallel:
> parallel_hds_isa_init() shouldn't fail, 2015-02-04), and you should
> preserve the logic of that commit.

I have to admit didn't consider CONFIG_PARALLEL when I wrote the commit.

>>> > You can move parallel_hds_isa_init and parallel_init to
>>> > hw/isa/isa-bus.c, or to a new file hw/isa/isa-devices.c.
>>> > 
>> Moving functions will cause abort with "Unknown device" error.
>
> This is the right behavior that we want: exit QEMU, not go on silently
> without the parallel port.

I agree silently ignoring command line options isn't nice, but it's
unfortunately what QEMU has always done.

In particular, -parallel is silently ignored with the vast majority of
machine types.  The few machine types that implement it silently ignore
it only when they fail to create the device.

I'm fine with changing -parallel to either create the device or fail.
Seems outside the scope of this series, though.

> If you do not like the abort, you should revert commit 4bc6a3e, and make
> parallel_hds_isa_init check for failure of parallel_init.  But for me
> it's okay to just let it abort.