Re: [Xen-devel] Suggestion: Improve hypercall Interface to get real return value

[Yanzhang Li <liyz@xxxxxxxxxx>]

Dear George,
Thank you very much for your comments. That really helps a lot.
Best Regards,
Yanzhang Li

----- Original Message -----
From: "George Dunlap" <dunlapg@xxxxxxxxx>
To: "Yanzhang Li" <liyz@xxxxxxxxxx>
Cc: xen-devel@xxxxxxxxxxxxx
Sent: un5efine5 7:05:32 PM
Subject: Re: [Xen-devel] Suggestion: Improve hypercall Interface to get real
 return value

On Wed, Dec 5, 2012 at 6:21 AM, Yanzhang Li < liyz@xxxxxxxxxx > wrote: 






Do you think this would be a good modification? 
Also, I am curious why the original design didn't do that. Is it a bug or is it 
designed that way intentionally? 
Any suggestions and comments will be highly appreciated. 


The reason we just return -1 is because that is the standard practice for Unix 
system libraries: to return -1 but set the error value in "errno". I couldn't 
tell you why Unix does this, but there's an advantage to following standard 
interfaces, because it reduces the surprise factor, and reduces the amount of 
information programmers need to keep in their head. 

Â-George 

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