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projects [2015-11-20 00:30]
joshtriplett Mark CONFIG_MULTI_USER items done.
projects [2017-06-13 22:27] (current)
joshtriplett New project: eliminate unused printing code
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   * Make individual syscalls or groups of syscalls optional. See the [[syscalls]] page for a list of syscalls that can't currently be compiled out.  (Note that in most cases you'll want to compile out the underlying kernel functionality exposed by those syscalls; if that functionality is not already optional, this will likely turn into a large project. ​ Also, you do not need to add a Kconfig option for each syscall; you can group a related family of syscalls under one option, especially if they all depend on the same infrastructure.)   * Make individual syscalls or groups of syscalls optional. See the [[syscalls]] page for a list of syscalls that can't currently be compiled out.  (Note that in most cases you'll want to compile out the underlying kernel functionality exposed by those syscalls; if that functionality is not already optional, this will likely turn into a large project. ​ Also, you do not need to add a Kconfig option for each syscall; you can group a related family of syscalls under one option, especially if they all depend on the same infrastructure.)
-    * In progress: sendfile, splice/​vmsplice,​ tee, adjtime/​adjtimex,​ iopl, ioperm +    * In progress: sendfile, splice/​vmsplice,​ tee, adjtime/​adjtimex,​ iopl, ioperm, pivot_root, prctl 
-    * Good targets: ​pivot_root, ​renameat2+    * Good targets: renameat2
   * Look at the directories and built-in.o files that show up in a tinyconfig build, and check for directories where all of the code depends (directly or indirectly) on a single configuration symbol. ​ (''​find -name built-in.o -size 8c''​ will find built-in.o files that contain no code.) in the Makefile for the parent directory, change obj-y to obj-$(CONFIG_THAT_SYMBOL),​ to stop the build system from recursing into that directory at all.  This doesn'​t directly make the kernel smaller, but makes the build faster and makes it easier to identify which code gets built in.   * Look at the directories and built-in.o files that show up in a tinyconfig build, and check for directories where all of the code depends (directly or indirectly) on a single configuration symbol. ​ (''​find -name built-in.o -size 8c''​ will find built-in.o files that contain no code.) in the Makefile for the parent directory, change obj-y to obj-$(CONFIG_THAT_SYMBOL),​ to stop the build system from recursing into that directory at all.  This doesn'​t directly make the kernel smaller, but makes the build faster and makes it easier to identify which code gets built in.
   * Compile out kernel/​time/​ntp.c,​ along with adjtimex and similar syscalls. (done)   * Compile out kernel/​time/​ntp.c,​ along with adjtimex and similar syscalls. (done)
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     * make most of sys.o configurable     * make most of sys.o configurable
     * make notifier.o configurable     * make notifier.o configurable
 +  * Allow board-specific DT parser removal. ​ From Josh, "... effectively compile in a parsed description and ditch the parser. Bonus if you can make the values parsed out of it into compile-time constants for constant folding."​ Jason Cooper <​jason@lakedaemon.net>​ is responsible for this idea.
  
 ====== Projects requiring toolchain changes ====== ====== Projects requiring toolchain changes ======
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   * Automatic structure re-layout to drop fields not referenced   * Automatic structure re-layout to drop fields not referenced
   * Dropping structure field assignments;​ mark dead fields with an attribute, ignore writes, error on reads   * Dropping structure field assignments;​ mark dead fields with an attribute, ignore writes, error on reads
 +  * Compile out support for specific format-string components from snprintf and family; would require some support from the toolchain to detect which ones get used in a build. Alternatively,​ replace all the non-human-targeted uses of snprintf with a call to an underlying helper function shared with snprintf, and then use dead code elimination to drop the unused ones.
projects.1447979405.txt.gz · Last modified: 2015-11-20 00:30 by joshtriplett