Am 17.07.2019 um 20:07 schrieb Tom Rini:
On Tue, Jul 16, 2019 at 10:30:36PM +0200, Simon Goldschmidt wrote:
This implements a stack usage check in SPL.
Many boards start up SPL to run code + data from one common, rather small SRAM. To implement a sophisticated SPL binary size limit on such boards, the stack size (as well as malloc size and global data size) must be subtracted from this SRAM size.
However, to do that properly, the stack size first needs to be known.
This patch adds a new Kconfig option:
- SPL_SYS_REPORT_STACK_F_USAGE: memset(0xaa) the whole area of the stack very early and check stack usage based on this constant later before the stack is switched to DRAM
Initializing the stack and checking it is implemented in weak functions, in case a board does not use the stack as saved in gd->start_addr_sp.
Signed-off-by: Simon Goldschmidt simon.k.r.goldschmidt@gmail.com
Very nice! I wish I had thought of something like that years ago when Wolfgang asked and I came up with the -fstack-usage stuff we have today.
Well, I think theoretically, a compile-time approach is better than what I did. However, that -fstack-usage thing did not work out for me (I'd have to look into that again), so I implemented this runtime check.
On the positive side, pre-relocation stack usage doesn't change too much, so the old rule of thumb of checking it once and the taking roughly the double as config option should be good ;-)
Regards, Simon