diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/guix.texi | 40 |
1 files changed, 38 insertions, 2 deletions
diff --git a/doc/guix.texi b/doc/guix.texi index 8381b388cc..09ed39213c 100644 --- a/doc/guix.texi +++ b/doc/guix.texi @@ -2160,8 +2160,32 @@ substituted to the reference to the @var{coreutils} package in the actual build code, and @var{coreutils} is automatically made an input to the derivation. Likewise, @code{#$output} (equivalent to @code{(ungexp output)}) is replaced by a string containing the derivation's output -directory name. The syntactic form to construct gexps is summarized -below. +directory name. + +@cindex cross compilation +In a cross-compilation context, it is useful to distinguish between +references to the @emph{native} build of a package---that can run on the +host---versus references to cross builds of a package. To that end, the +@code{#+} plays the same role as @code{#$}, but is a reference to a +native package build: + +@example +(gexp->derivation "vi" + #~(begin + (mkdir #$output) + (system* (string-append #+coreutils "/bin/ln") + "-s" + (string-append #$emacs "/bin/emacs") + (string-append #$output "/bin/vi"))) + #:target "mips64el-linux") +@end example + +@noindent +In the example above, the native build of @var{coreutils} is used, so +that @command{ln} can actually run on the host; but then the +cross-compiled build of @var{emacs} is referenced. + +The syntactic form to construct gexps is summarized below. @deffn {Scheme Syntax} #~@var{exp} @deffnx {Scheme Syntax} (gexp @var{exp}) @@ -2190,6 +2214,13 @@ This is like the form above, but referring explicitly to the @var{package-or-derivation} produces multiple outputs (@pxref{Packages with Multiple Outputs}). +@item #+@var{obj} +@itemx #+@var{obj}:output +@itemx (ungexp-native @var{obj}) +@itemx (ungexp-native @var{obj} @var{output}) +Same as @code{ungexp}, but produces a reference to the @emph{native} +build of @var{obj} when used in a cross compilation context. + @item #$output[:@var{output}] @itemx (ungexp output [@var{output}]) Insert a reference to derivation output @var{output}, or to the main @@ -2202,6 +2233,11 @@ This only makes sense for gexps passed to @code{gexp->derivation}. Like the above, but splices the contents of @var{lst} inside the containing list. +@item #+@@@var{lst} +@itemx (ungexp-native-splicing @var{lst}) +Like the above, but refers to native builds of the objects listed in +@var{lst}. + @end table G-expressions created by @code{gexp} or @code{#~} are run-time objects |