Hi Albert,
On 31 January 2015 at 15:36, Albert ARIBAUD albert.u.boot@aribaud.net wrote:
Hello Simon,
On Mon, 26 Jan 2015 08:34:21 -0700, Simon Glass sjg@chromium.org wrote:
At present SPL uses a single stack, either CONFIG_SPL_STACK or CONFIG_SYS_INIT_SP_ADDR. Since some SPL features (such as MMC and environment) require a lot of stack, some boards set CONFIG_SPL_STACK to point into SDRAM. They then set up SDRAM very early, before board_init_f(), so that the larger stack can be used.
This is an abuse of lowlevel_init(). That function should only be used for essential start-up code which cannot be delayed. An example of a valid use is when only part of the SPL code is visible/executable, and the SoC must be set up so that board_init_f() can be reached. It should not be used for SDRAM init, console init, etc.
Add a CONFIG_SPL_STACK_R option, which allows the stack to be moved to a new address before board_init_r() is called in SPL.
The expected SPL flow (for CONFIG_SPL_FRAMEWORK) is now:
Execution starts with start.S. Two main functions can be provided by the board implementation. The purpose and limitations of each is described below. After that, the common board_init_r() is called to perform the SPL task.
lowlevel_init(): - purpose: essential init to permit execution to reach board_init_f() - no global_data, but there is a stack
lowlevel_init() does not have a stack for all ARM CPUs, e.g. for arm926ejs it has none; and I don't see any code in this patch that provides one. If we need lowlevel_init to have a stack, then this stack should be set up in crt0.S and lowlevel_init called from there (which I would be fine with, btw).
OK, so I should adjust this comment I think. Is that the only action?
- no global_data, but may be a stack (e.g. for armv7)
[snip]
Regards, Simon