On Mon, Jun 21, 2021 at 11:35:24AM +0200, Pavel Hrdina wrote: > On Sun, Jun 20, 2021 at 05:10:40PM +0800, Jiatong Shen wrote: > > Hello community, > > > > I am looking at building and packaging libvirt source code. I am seeing > > from commit > > https://github.com/libvirt/libvirt/commit/83ff55b5a2618d32f623d7ca0b6f9c28b7253972 > > `driver_remote` is defaulting to auto which is different from enabled > > before. I am curious what does auto mean? does it mean that meson will take > > over and determine if driver_remote should be enabled or we have to write > > more logic in meson.build? currently it seems there is no effort to auto > > determine driver_remote. I think it is interesting because > > https://github.com/libvirt/libvirt/blob/54b602019d7dfa94a6c52ef7aa3abdfaa93ed233/meson.build#L1178 > > sasl seems required remote_driver to have a value of enabled... > > Hi, > > I see how this may be confusing. The current code is correct and there > is no need to change anything as this one way how it can be done with > meson. > > If some option is 'feature' type and the default value is set to 'auto' > this is what meson returns: > > get_option('opt').disabled() -> false > get_option('opt').auto() -> true > get_option('opt').enabled() -> false > > In the case of 'driver_remote' option we have the following check: > > if not get_option('driver_remote').disabled() > > which means that it will disable 'driver_remote' only if user calls > meson with `-Ddriver_remote=disabled`. > > If you look closer to the following lines you will see that we also > check for xdr_dep. If xdr_dep is missing and 'driver_remote' is set > to 'auto' it will not be enabled as XDR is required, but if > 'driver_remote' is set to 'enabled' but user calling meson with > `-Ddriver_remote=enabled` meson will fail with proper error message. > > Before the changes done by the first commit you mentioned the > 'driver_remote' was always enabled and if XDR was missing it always > failed and user had to explicitly use `-Ddriver_remote=disabled` on > systems where XDR is not available or if the user was not interested > in having 'driver_remote' available. I will add that, when packaging libvirt, it's recommended to explicitly pass -Dfeature=enabled/disabled for each and every feature instead of relying on libvirt's autodetection getting things right: this ensures that the build either exactly matches your expectations or fails with a useful error message. -- Andrea Bolognani / Red Hat / Virtualization
