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From: Peter Maydell <peter.maydell@linaro.org>
Date: Tue, 28 Mar 2017 13:14:29 +0100
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Subject: Re: [Qemu-devel] [PATCH for-2.9] Fix check for target OS support
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To: Stefan Weil <sw@weilnetz.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>, QEMU Developer <qemu-devel@nongnu.org>

On 28 March 2017 at 13:07, Stefan Weil <sw@weilnetz.de> wrote:
> Am 28.03.2017 um 09:10 schrieb Peter Maydell:
>> On 27 March 2017 at 21:11, Stefan Weil <sw@weilnetz.de> wrote:
>>>  *)
>>> -  error_exit "Unsupported host OS $targetos"
>>> +  supported_os="no"
>> This was deliberately an error_exit because anything
>> going down that path got the Linux defines/includes by
>> accident and we thought that would not work on
>> anything else. What was using it? If we need an extra
>> entry in the case statement we can add one.
>
> It remains an error (that's why I introduced a third state for
> supported_os), but must be handled later, after processing
> a potential --help option.

I think the right fix for this is to special case --help
to bypass more checks and to happen earlier. For instance
if you don't happen to have a 'python' on your PATH then
we do this:

netbsdvm# ./configure --help

ERROR: Python not found. Use --python=/path/to/python

I'll have a go at writing a patch.

thanks
-- PMM