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From: Peter Maydell <peter.maydell@linaro.org>
Date: Mon, 9 Nov 2015 15:47:00 +0000
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Subject: Re: [Qemu-devel] [PATCH] hw/arm/virt: error_report cleanups
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To: Markus Armbruster <armbru@redhat.com>
Cc: Andrew Jones <drjones@redhat.com>, qemu-arm@nongnu.org, QEMU Developers <qemu-devel@nongnu.org>

On 9 November 2015 at 10:21, Markus Armbruster <armbru@redhat.com> wrote:
> Peter Maydell <peter.maydell@linaro.org> writes:
>
>> On 9 November 2015 at 07:44, Markus Armbruster <armbru@redhat.com> wrote:
>>> For consistency, error messages should be a phrase, not a full sentence,
>>> let alone a paraphraph.
>>
>> This is in direct conflict with wanting them to be actually useful
>> to users :-(
>
> I appreciate your drive for useful error messages.  Judging from the
> error messages we got, it's a rare thing.
>
> Let me rephrase.  The error message proper (the thing emitted by
> error_report()) should be a phrase, and it should be short and to the
> point.  It can be followed by hints.  Compare:
>
>     qemu-system-arm: Unable to determine GIC version supported by host. KVM acceleration is probably not supported.
>
> and
>
>     qemu-system-arm: Unable to determine GIC version supported by host
>     KVM acceleration is probably not supported
>
> I prefer the latter.  The error message proper is short and to the
> point.  The hint points to the most probable cause.  Sensible line
> lengths.

I agree that the latter is preferable; I had been under the
impression that we weren't allowed to use newlines in error
messages, though...

> By the way, the error.h API supports this message + hints convention
> since commit 50b7b00.

Thanks, I had missed this useful improvement to the API.
How does it work in cases like this where we don't have
an Error* to fill in?

thanks
-- PMM