Example:
#arch/x86/Makefile
cflags-y += $(shell \
- if [ $(call cc-version) -ge 0300 ] ; then \
+ if [ $(cc-version) -ge 0300 ] ; then \
echo "-mregparm=3"; fi ;)
In the above example, -mregparm=3 is only used for gcc version greater
than or equal to gcc 3.0.
cc-ifversion
- cc-ifversion tests the version of $(CC) and equals last argument if
- version expression is true.
+ cc-ifversion tests the version of $(CC) and equals the fourth parameter
+ if version expression is true, or the fifth (if given) if the version
+ expression is false.
Example:
#fs/reiserfs/Makefile
Example:
#arch/powerpc/Makefile
- $(Q)if test "$(call cc-fullversion)" = "040200" ; then \
+ $(Q)if test "$(cc-fullversion)" = "040200" ; then \
echo -n '*** GCC-4.2.0 cannot compile the 64-bit powerpc ' ; \
false ; \
fi
Additional files can be specified in kbuild makefiles by use of $(clean-files).
Example:
- #drivers/pci/Makefile
- clean-files := devlist.h classlist.h
+ #lib/Makefile
+ clean-files := crc32table.h
When executing "make clean", the two files "devlist.h classlist.h" will be
deleted. Kbuild will assume files to be in the same relative directory as the
- Makefile except if an absolute path is specified (path starting with '/').
+ Makefile, except if prefixed with $(objtree).
To delete a directory hierarchy use:
#scripts/package/Makefile
clean-dirs := $(objtree)/debian/
- This will delete the directory debian, including all subdirectories.
- Kbuild will assume the directories to be in the same relative path as the
- Makefile if no absolute path is specified (path does not start with '/').
+ This will delete the directory debian in the toplevel directory, including all
+ subdirectories.
To exclude certain files from make clean, use the $(no-clean-files) variable.
This is only a special case used in the top level Kbuild file:
config TREE_RCU
bool "Tree-based hierarchical RCU"
depends on !PREEMPT && SMP
- select IRQ_WORK
help
This option selects the RCU implementation that is
designed for very large SMP system with hundreds or
config PREEMPT_RCU
bool "Preemptible tree-based hierarchical RCU"
depends on PREEMPT
- select IRQ_WORK
help
This option selects the RCU implementation that is
designed for very large SMP systems with hundreds or
endchoice
+config SRCU
+ bool
+ help
+ This option selects the sleepable version of RCU. This version
+ permits arbitrary sleeping or blocking within RCU read-side critical
+ sections.
+
config TASKS_RCU
bool "Task_based RCU implementation using voluntary context switch"
default n
+ select SRCU
help
This option enables a task-based RCU implementation that uses
only voluntary context switch (not preemption!), idle, and
config RCU_KTHREAD_PRIO
int "Real-time priority to use for RCU worker threads"
- range 1 99
- depends on RCU_BOOST
- default 1
+ range 1 99 if RCU_BOOST
+ range 0 99 if !RCU_BOOST
+ default 1 if RCU_BOOST
+ default 0 if !RCU_BOOST
help
This option specifies the SCHED_FIFO priority value that will be
assigned to the rcuc/n and rcub/n threads and is also the value
endif
-config INIT_FALLBACK
- bool "Fall back to defaults if init= parameter is bad"
- default y
- help
- If enabled, the kernel will try the default init binaries if an
- explicit request from the init= parameter fails.
-
- This can have unexpected effects. For example, booting
- with init=/sbin/kiosk_app will run /sbin/init or even /bin/sh
- if /sbin/kiosk_app cannot be executed.
-
- The default value of Y is consistent with historical behavior.
- Selecting N is likely to be more appropriate for most uses,
- especially on kiosks and on kernels that are intended to be
- run under the control of a script.
-
config CC_OPTIMIZE_FOR_SIZE
bool "Optimize for size"
help
- Enabling this option will pass "-Os" instead of "-O2" to gcc
- resulting in a smaller kernel.
+ Enabling this option will pass "-Os" instead of "-O2" to
+ your compiler resulting in a smaller kernel.
If unsure, say N.
depends on HAVE_PERF_EVENTS
select ANON_INODES
select IRQ_WORK
+ select SRCU
help
Enable kernel support for various performance events provided
by software and hardware.