| From | Rusty Russell <> | Subject | Re: [patch 12/17] Immediate Values - Kconfig menu in EMBEDDED | Date | Thu, 10 Apr 2008 13:23:55 +1000 |
| |
On Thursday 10 April 2008 01:08:41 Mathieu Desnoyers wrote: > +config IMMEDIATE > + default y if !DISABLE_IMMEDIATE
Wouldn't it be simlpler to roll DISABLE_IMMEDIATE into this?
ie. default y depends on HAVE_IMMEDIATE bool "Immediate value optimization" if EMBEDDED help Immediate values are used as read-mostly variables that are rarely updated. They use code patching to modify the values inscribed in the instruction stream. It provides a way to save precious cache lines that would otherwise have to be used by these variables.
It consumes slightly more memory and requires to modify the instruction stream each time a variable is updated. Should really be disabled for embedded systems with read-only text.
Cheers, Rusty.
|