Re: [Xen-devel] [PATCH] tools/libxenforeignmemory: add a call to restrict the handle

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Andrew Cooper [mailto:amc96@xxxxxxxxxxxxxxxx] On Behalf Of
> Andrew Cooper
> Sent: 27 March 2017 09:16
> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>; xen-devel@xxxxxxxxxxxxxxxxxxxx
> Cc: Ian Jackson <Ian.Jackson@xxxxxxxxxx>; Julien Grall
> <julien.grall@xxxxxxx>; Wei Liu <wei.liu2@xxxxxxxxxx>
> Subject: Re: [Xen-devel] [PATCH] tools/libxenforeignmemory: add a call to
> restrict the handle
> 
> On 27/03/2017 09:06, Paul Durrant wrote:
> >> -----Original Message-----
> >> From: Xen-devel [mailto:xen-devel-bounces@xxxxxxxxxxxxx] On Behalf Of
> >> Paul Durrant
> >> Sent: 24 March 2017 20:24
> >> To: Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>; xen-
> >> devel@xxxxxxxxxxxxxxxxxxxx
> >> Cc: Ian Jackson <Ian.Jackson@xxxxxxxxxx>; Julien Grall
> >> <julien.grall@xxxxxxx>; Wei Liu <wei.liu2@xxxxxxxxxx>
> >> Subject: Re: [Xen-devel] [PATCH] tools/libxenforeignmemory: add a call
> to
> >> restrict the handle
> >>
> >>> -----Original Message-----
> >>> From: Andrew Cooper
> >>> Sent: 24 March 2017 20:10
> >>> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>; xen-
> >> devel@xxxxxxxxxxxxxxxxxxxx
> >>> Cc: Wei Liu <wei.liu2@xxxxxxxxxx>; Ian Jackson
> <Ian.Jackson@xxxxxxxxxx>;
> >>> Julien Grall <julien.grall@xxxxxxx>
> >>> Subject: Re: [Xen-devel] [PATCH] tools/libxenforeignmemory: add a call
> to
> >>> restrict the handle
> >>>
> >>> On 22/03/17 11:25, Paul Durrant wrote:
> >>>> diff --git a/tools/libs/foreignmemory/libxenforeignmemory.map
> >>> b/tools/libs/foreignmemory/libxenforeignmemory.map
> >>>> index df206b3..5c9806c 100644
> >>>> --- a/tools/libs/foreignmemory/libxenforeignmemory.map
> >>>> +++ b/tools/libs/foreignmemory/libxenforeignmemory.map
> >>>> @@ -4,5 +4,6 @@ VERS_1.0 {
> >>>>                  xenforeignmemory_close;
> >>>>                  xenforeignmemory_map;
> >>>>                  xenforeignmemory_unmap;
> >>>> +                xenforeignmemory_restrict;
> >>>>          local: *; /* Do not expose anything by default */
> >>>>  };
> >>> This isn't correct.
> >>>
> >>> New functions like this need to bump at least the SO minor version, like
> >>> c/s f1446de4ba
> >>>
> >> Sorry, yes, I forgot these libraries are supposed to be stable now.
> >>
> >>> Fixing this is a blocker to releasing 4.9
> >>>
> >> I'll submit a patch on Monday.
> > Actually, on second thoughts, do we want to bump the version for all
> changes or just incompatible ones? I added a call here so it shouldn't break
> any older application compiling against this library.
> 
> You must bump the versions; the version information gets embedded as
> part of the dynamic linkage of the application built against
> libxenforeignmemory.
> 
> In particular, you need to prevent an application built now from
> referencing xenforeignmemory_restrict@1.0 because the version 1.0
> shipped in all earlier versions of Xen lacked this function.
> 
> Not bumping the version now will result in newer applications being
> built which the dynamic loader thinks will work with older versions of
> the library, rather than correctly identifying that a newer version of
> the library is required.
> 
> As with other things in staging, it can get away with only being bumped
> once per Xen release, but it must always be bumped at the first change.
> 

Ok. I'll send a patch today then.

  Paul

> ~Andrew
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