On 11 July 2014 05:23, Simon Glass sjg@chromium.org wrote:
If we are to have driver model before relocation we need to support some way of calling memory allocation routines.
The standard malloc() is pretty complicated:
- It uses some BSS memory for its state, and BSS is not available before
relocation
- It supports algorithms for reducing memory fragmentation and improving
performace of free(). Before relocation we could happily just not support free().
- It includes about 4KB of code (Thumb 2) and 1KB of data. However since
this has been loaded anyway this is not really a problem.
The simplest way to support pre-relocation malloc() is to reserve an area of memory and allocate it in increasing blocks as needed. This implementation does this.
To enable it, you need to define the size of the malloc() pool as described in the README. It will be located above the pre-relocation stack on supported architectures.
Note that this implementation is only useful on machines which have some memory available before dram_init() is called - this includes those that do no DRAM init (like tegra) and those that do it in SPL (quite a few boards). Enabling driver model preior to relocation for the rest of the boards is left for a later exercise.
Signed-off-by: Simon Glass sjg@chromium.org
Applied to dm/master.