Changeset 3621 in MondoRescue for branches/3.3/mindi-busybox/docs/keep_data_small.txt

Timestamp:

Dec 20, 2016, 4:07:32 PM (7 years ago)

Author:

Bruno Cornec

Message:

New 3?3 banch for incorporation of latest busybox 1.25. Changing minor version to handle potential incompatibilities.

Location:

branches/3.3

Files:

• . (copied) (copied from branches/3.2 )
• mindi-busybox/docs/keep_data_small.txt (modified) (3 diffs)

branches/3.3/mindi-busybox/docs/keep_data_small.txt

@@ -104 +104 @@
     SET_PTR_TO_GLOBALS(xzalloc(sizeof(G)));
 
-Typically it is done in <applet>_main().
+Typically it is done in <applet>_main(). Another variation is
+to use stack:
+
+int <applet>_main(...)
+{
+#undef G
+    struct globals G;
+    memset(&G, 0, sizeof(G));
+    SET_PTR_TO_GLOBALS(&G);
 
 Now you can reference "globals" by G.a, G.buf and so on, in any function.
@@ -137 +145 @@
 #define dev_fd (G.dev_fd)
 #define sector (G.sector)
-
-
-        Word of caution
-
-If applet doesn't use much of global data, converting it to use
-one of above methods is not worth the resulting code obfuscation.
-If you have less than ~300 bytes of global data - don't bother.
 
 
@@ -224 +225 @@
 
         Keeping code small
+
+Use scripts/bloat-o-meter to check whether introduced changes
+didn't generate unnecessary bloat. This script needs unstripped binaries
+to generate a detailed report. To automate this, just use
+"make bloatcheck". It requires busybox_old binary to be present,
+use "make baseline" to generate it from unmodified source, or
+copy busybox_unstripped to busybox_old before modifying sources
+and rebuilding.
 
 Set CONFIG_EXTRA_CFLAGS="-fno-inline-functions-called-once",