On 32-bit kernel we need ~26k per applet.
+Script:
+
+i=1000; while test $i != 0; do
+ echo -n .
+ busybox sleep 30 &
+ i=$((i - 1))
+done
+echo
+wait
+
(Data from NOMMU arches are sought. Provide 'size busybox' output too)
ptr_to_globals is declared as constant pointer.
This helps gcc understand that it won't change, resulting in noticeably
-smaller code. In order to assign it, use PTR_TO_GLOBALS macro:
+smaller code. In order to assign it, use SET_PTR_TO_GLOBALS macro:
- PTR_TO_GLOBALS = xzalloc(sizeof(G));
+ SET_PTR_TO_GLOBALS(xzalloc(sizeof(G)));
Typically it is done in <applet>_main().
If you have less than ~300 bytes of global data - don't bother.
+ Finding non-shared duplicated strings
+
+strings busybox | sort | uniq -c | sort -nr
+
+
gcc's data alignment problem
The following attribute added in vi.c:
text data bss dec hex filename
634416 2736 23856 661008 a1610 busybox
632580 2672 22944 658196 a0b14 busybox_noalign
+
+
+
+ Keeping code small
+
+Set CONFIG_EXTRA_CFLAGS="-fno-inline-functions-called-once",
+produce "make bloatcheck", see the biggest auto-inlined functions.
+Now, set CONFIG_EXTRA_CFLAGS back to "", but add NOINLINE
+to some of these functions. In 1.16.x timeframe, the results were
+(annotated "make bloatcheck" output):
+
+function old new delta
+expand_vars_to_list - 1712 +1712 win
+lzo1x_optimize - 1429 +1429 win
+arith_apply - 1326 +1326 win
+read_interfaces - 1163 +1163 loss, leave w/o NOINLINE
+logdir_open - 1148 +1148 win
+check_deps - 1148 +1148 loss
+rewrite - 1039 +1039 win
+run_pipe 358 1396 +1038 win
+write_status_file - 1029 +1029 almost the same, leave w/o NOINLINE
+dump_identity - 987 +987 win
+mainQSort3 - 921 +921 win
+parse_one_line - 916 +916 loss
+summarize - 897 +897 almost the same
+do_shm - 884 +884 win
+cpio_o - 863 +863 win
+subCommand - 841 +841 loss
+receive - 834 +834 loss
+
+855 bytes saved in total.
+
+scripts/mkdiff_obj_bloat may be useful to automate this process: run
+"scripts/mkdiff_obj_bloat NORMALLY_BUILT_TREE FORCED_NOINLINE_TREE"
+and select modules which shrank.