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Re: [Qemu-devel] [PATCH v2 07/10] qdev: Eliminate "global not used" warn
Re: [Qemu-devel] [PATCH v2 07/10] qdev: Eliminate "global not used" warning
Thu, 23 Jun 2016 10:17:55 +0200
Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux)
Eduardo Habkost <address@hidden> writes:
> qdev_prop_check_globals() tries to warn the user if a given
> -global option was not used. But it does that only if the device
> is not hotpluggable.
Because then the option will never be used.
> The warning also makes it harder for management code or people
> that write their own scripts or config files: there's no way to
> know if a given -global option will trigger a warning or not,
> because we don't have any introspection mechanism to check if a
> machine-type instantiates a given device or not.
Well, there is: create the machine, look for the device. I guess what
you're trying to say is that there's no way to *predict* what a machine
type will instantiate, at least not until after the fact.
Suggest "will instantiate a given device".
> The warning is also the only reason we have the 'user_provided'
> and 'used' fields in struct GlobalProperty. Removing the check
> will let us simplify the code.
> In other words, the warning is nearly useless and gets in our way
> and our users' way. Remove it.
Well, telling me that I gave a non-sensical option isn't always useless.
I might have fat-fingered something, or be confused about my devices.
Say I give -global PIIX4_PM.disable_s3=1. Does what I want with an
i440FX machine type. Except it does nothing with -no-acpi or with a Q35
machine type. The former is harmless enough, but the latter is a
mistake; I need to say -global ICH9-LPC.disable_s3=1. Before this
patch, I get a warning in either case.
Is this warning really useless?