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Diffstat (limited to 'docs/manual')
| -rw-r--r-- | docs/manual/ccache-support.txt | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/docs/manual/ccache-support.txt b/docs/manual/ccache-support.txt index 992471dbf7..f6746ad7d8 100644 --- a/docs/manual/ccache-support.txt +++ b/docs/manual/ccache-support.txt @@ -33,3 +33,23 @@ make CCACHE_OPTIONS="--max-size=5G" ccache-options # zero statistics counters make CCACHE_OPTIONS="--zero-stats" ccache-options ----------------- + ++ccache+ makes a hash of the source files and of the compiler options. +If a compiler option is different, the cached object file will not be +used. Many compiler options, however, contain an absolute path to the +staging directory. Because of this, building in a different output +directory would lead to many cache misses. + +To avoid this issue, buildroot has the +Use relative paths+ option +(+BR2_CCACHE_USE_BASEDIR+). This will rewrite all absolute paths that +point inside the output directory into relative paths. Thus, changing +the output directory no longer leads to cache misses. + +A disadvantage of the relative paths is that they also end up to be +relative paths in the object file. Therefore, for example, the debugger +will no longer find the file, unless you cd to the output directory +first. + +See https://ccache.samba.org/manual.html#_compiling_in_different_directories[the +ccache manual's section on "Compiling in different directories"] for +more details about this rewriting of absolute paths. |
