Re: [gentoo-user] xen: How to enable a non-existant USE flag? (xen doesn't work)

[Alan McKinnon]

On 13/07/2015 19:22, hw wrote:
>
> So what happened to the 'hvm' USE flag of the "xen-tools" package?
>
> http://gentoobrowse.randomdan.homeip.net/package/app-emulation/xen-tools
> says there is such a flag.  However:
>
>
> moonflo ~ # equery uses xen-tools
> [ Legend : U - final flag setting for installation]
> [        : I - package is installed with flag     ]
> [ Colors : set, unset                             ]
>  * Found these USE flags for app-emulation/xen-tools-4.5.1-r1:
>  U I
>  - - api                      : Build the C libxenapi bindings
>  - - custom-cflags            : Build with user-specified CFLAGS
> (unsupported)
>  - - debug                    : Enable extra debug codepaths, like
> asserts and extra output. If you want to get meaningful backtraces see
>
> https://wiki.gentoo.org/wiki/Project:Quality_Assurance/Backtraces
>  - - doc                      : Add extra documentation (API, Javadoc,
> etc). It is recommended to enable per package instead of globally
>  - - flask                    : Enable the Flask XSM module from NSA
>  - - ovmf                     : Enable support to boot UEFI guest vm,
> needed by hvm
>  + + pam                      : Enable pam support
>  - - pygrub                   : Install the pygrub boot loader
>  - - python                   : Add optional support/bindings for the
> Python language
>  + + python_targets_python2_7 : Build with Python 2.7
>  - - qemu                     : Enable IOEMU support via the use of qemu-dm
>  - - screen                   : Enable support for running domain U
> console in an app-misc/screen session
>  - - static-libs              : Build static versions of dynamic
> libraries as well
>  - - system-qemu              : Using app-emulation/qemu instead of the
> bundled one
>  - - system-seabios           : Using sys-firmware/seabios instead of
> the bundled one
> moonflo ~ #
>
>
> So there is no such flag.  Apparently my installation is missing
> 'hvmloader', and I'm guessing that I would have that if I could enable
> the 'hmv' USE flag.
>
> How do I enable a USE flag that doesn't seem to exist?
>


You don't enable a USE flag that does not exist. How could you? It's not
there.


A primer on USE flags:

These set *optional* features for build time, usually by setting options
to ./configure at build time (or some equivalent means). If a USE flag
goes away, it usually means the feature is no longer optional but now
permanently enabled (or sometimes not enabled at all). Or perhaps the
upstream build system changed, and USE must correspondingly change.

If something that used to work and now doesn't after USE is modified by
the dev, then that is a bug, so report it. Sometimes an optional feature
that never really worked at all is removed by upstream, which means the
USE flag goes away, and that is a discussion you must have with upstream
if it breaks stuff for you.

Either way, your start point is to touch base with the Gentoo maintainer
of the package.



-- 
Alan McKinnon
alan.mckinnon@×××××.com