to file specifications. The prefixes are arranged in a stack, and
nest, so that file, object, and include specifications are normalized,
and all end up relative to the kernel compile directory.
For example, in the kernel config file:
# Pull in config fragments for kernel crypto
prefix ../crypto-us/sys # push it
cinclude "conf/files.crypto-us" # include it if it's there
prefix # pop it
and in files.crypto-us:
file netinet6/esp_core.c ipsec & ipsec_esp
file netinet6/esp_output.c ipsec & ipsec_esp
file netinet6/esp_input.c ipsec & ipsec_esp
...generates the following in the kernel Makefile:
$S/../crypto-us/sys/netinet6/esp_core.c \
$S/../crypto-us/sys/netinet6/esp_output.c \
$S/../crypto-us/sys/netinet6/esp_input.c \
By placing this all in the kernel config file, all the magic involved in
reaching into non-standard kernel source directories is placed into a file
that the user is expected to edit anyway, and reasonable examples (and
sane defaults, for typical source checkouts) can be provided.
Syntax is like the `file' keyword; e.g.:
object arch/i386/i386/mumble.o [mumble] [needs-flag]
Largely from Michael Richardson in PR 3833, with some changes by me.
right/consistent. If you had something like:
file file.c foo bar baz needs-flag
and any one of foo, bar, or baz caused it to be brought into the compile,
in the header you'd end up with:
#define NFOO 1
#define NBAR 1
#define NBAZ 1
even if only one of them were selected. Other headers might have had a
different (inconsistent) set of definitions, depending on whether any of
their components were included, and any files necessary for the unspecified
options would not actually be present in the Makefile files list. The
correct behaviour for the example above if only 'foo' is selected by
the config file is:
#define NFOO 1
#define NBAR 0
#define NBAZ 0
which is what config now does. This bug has been present for a while.
(I don't know for sure that it was present in 4.4-Lite2, but from looking
at the Lite2 config sources, it appears to be there.)
thorpej