Re: [Xen-devel] Regression in xen-unstable due to commit 3802ecbaa9eb36

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Thu, May 16, 2019 at 01:38:57PM +0200, Olaf Hering wrote:
> Am Thu, 16 May 2019 12:24:50 +0100
> schrieb Wei Liu <wei.liu2@xxxxxxxxxx>:
> 
> > The problem with this approach is that it doesn't help existing libxl
> > users. They will need to be fixed by calling this new API.
> 
> If the API needs to be changed, a LIBXL_HAVE_ came with the change.
> 
> I'm not sure how to fix this without changing some API.
> libxl__domain_build_info_setdefault would need a d_config to make a
> usable decision. The callers do not have a d_config. And what their
> calles have is an incomplete d_config because libxl lacks a public API
> to properly populate missing defaults in d_config.
> 
> To me it looks like something like 
> libxl_domain_config_finish(libxl_domain_config*)
> is missing now.
> 
> Maybe I am just misunderstanding what you trying to say, but to me it
> looks like freemem() would need to call an updated libxl public API
> anyway. Surely not freemem itself, but xl:create_domain as a whole.

Yes, that's what I want to avoid if possible. xl is just one of the
users of libxl. You will likely need to change libvirt as well.

Adding new APIs and defining LIBXL_HAVE won't get you out of this hole.
Yes you can add new APIs and new users are free to use them, but You
still need to retain backward compatibility somehow.

Wei.

> 
> Olaf



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