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Date:   Tue, 18 Apr 2023 07:55:31 -0500
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Subject: Re: [PATCH v11 24/26] virt: gunyah: Add irqfd interface
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To:     Elliot Berman <quic_eberman@quicinc.com>,
        Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
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        Konrad Dybcio <konrad.dybcio@linaro.org>,
        Arnd Bergmann <arnd@arndb.de>,
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From:   Alex Elder <elder@linaro.org>
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On 4/17/23 5:55 PM, Elliot Berman wrote:
>>>
>>> +struct gh_fn_irqfd_arg {
>>> +    __u32 fd;
>>
>> Should the "fd" field be signed?  Should it be an int?  (Perhaps
>> you're trying to define a fixed kernel API, so __s32 if signed would
>> be better.)
>>
> 
> It looked to me like some interfaces use __u32 and some use __s32. Is 
> one technically correct?

Good question.  It depends on how you use it.

It's a file descriptor, so it should be an int, and it appears
that's always a 32-bit signed (for 32 and 64 bit machines).
So the size seems to be right.

Whether it's signed or not I think depends on whether you
ever save an error value in this field.  I doubt you do,
but if you do, it should be signed.  Otherwise, the largest
value will never exceed INT_MAX/S32_MAX; and in that case
either is fine.

Will Gunyah ever run on a 32-bit machine?

					-Alex