From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [PATCH RFC] make error codes a formal part of the ABI Date: Tue, 13 Jan 2015 16:35:52 +0000 Message-ID: <1421166952.19103.148.camel@eu.citrix.com> References: <54B5540A02000078000547D4@mail.emea.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1YB4Rj-0003FI-1u for xen-devel@lists.xenproject.org; Tue, 13 Jan 2015 16:35:59 +0000 In-Reply-To: <54B5540A02000078000547D4@mail.emea.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: Keir Fraser , Stefano Stabellini , Andrew Cooper , Tim Deegan , xen-devel , Ian Jackson List-Id: xen-devel@lists.xenproject.org On Tue, 2015-01-13 at 16:21 +0000, Jan Beulich wrote: > Now that we have two cases where patches against hvmloader got > submitted needing to include the hypervisor's errno.h (for the host's > system header not necessarily reflecting the correct numbers), take > this as a strong sign that we need to make the error return values part > of the hypervisor ABI (which de-fact they've always been). Yes, I think this is a good move. > Signed-off-by: Jan Beulich > --- > There's on small block commented with TBD left in the public header. > This is the main reason for the submission being RFC. While we don't > currently use these error codes, I'm not sure if we should leave all > or some of them out for the time being. I say lets omit any we don't use for now. > --- /dev/null > +++ b/xen/include/public/errno.h > @@ -0,0 +1,94 @@ > +#ifndef __XEN_PUBLIC_ERRNO_H__ > + > +#ifndef __ASSEMBLY__ > + > +#define XEN_ERRNO(name, value) XEN_##name = value, > +enum xen_errno { The switch to an enum doesn't seem related to the main purpose of the patch, unless I'm missing something? > +#else /* !__ASSEMBLY__ */ > + > +#define XEN_ERRNO(name, value) .equ XEN_##name, value So here public/errno.h defines it's own XEN_ERRNO for ASM vs none. But then later xen/errno.h also defines it before including the public version. Also the enum xen_errno seems to be similarly duplicated. (I suspect you changed your mind and forgot to save one or the other file?). I think the includer chooses the namespace approach makes most sense. (I suppose someone needs to patch libxc et al to actually use this) > + > +#endif /* __ASSEMBLY__ */ > + > +/* ` enum neg_errnoval { [ -Efoo for each Efoo in the list below ] } */ > +/* ` enum errnoval { */ > + > +#endif /* __XEN_PUBLIC_ERRNO_H__ */ > + > +#ifdef XEN_ERRNO > + > +XEN_ERRNO(EPERM, 1) /* Operation not permitted */ > +XEN_ERRNO(ENOENT, 2) /* No such file or directory */ > +XEN_ERRNO(ESRCH, 3) /* No such process */ > +#ifdef __XEN__ > +XEN_ERRNO(EINTR, 4) /* Interrupted system call */ > +#endif I take it this is because something prevents this value ever getting exposes to userspace? (Continuations?). I think keeping that away from guest API is a good idea, but if it's completely internal perhaps we should move it up into a region which we reserve for ourselves? Ian.