[U-Boot] [PATCH] arm: socfpga: provide default SPL_SIZE_LIMIT for gen5

[Simon Goldschmidt]

On 13.06.19 22:14, Marek Vasut wrote:
> On 6/13/19 9:50 PM, Simon Goldschmidt wrote:
>> This provides an SPL_SIZE_LIMIT that makes the build check that the SPL
>> binary loaded from flash fits into the SRAM (64 KiB) and leaves enough
>> room for global data, heap  and stack (512 bytes assumed stack usage).
>>
>> Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt at gmail.com>
>> ---
>>
>>   arch/arm/mach-socfpga/Kconfig | 8 ++++++++
>>   1 file changed, 8 insertions(+)
>>
>> diff --git a/arch/arm/mach-socfpga/Kconfig b/arch/arm/mach-socfpga/Kconfig
>> index 48f02f08d4..1d914648e3 100644
>> --- a/arch/arm/mach-socfpga/Kconfig
>> +++ b/arch/arm/mach-socfpga/Kconfig
>> @@ -3,6 +3,12 @@ if ARCH_SOCFPGA
>>   config NR_DRAM_BANKS
>>   	default 1
>>   
>> +config SPL_SIZE_LIMIT
>> +	default 65536 if TARGET_SOCFPGA_GEN5
>> +
>> +config SPL_SIZE_LIMIT_PROVIDE_STACK
>> +	default 0x200 if TARGET_SOCFPGA_GEN5
>> +
>>   config SPL_STACK_R_ADDR
>>   	default 0x00800000 if TARGET_SOCFPGA_GEN5
>>   
>> @@ -49,6 +55,8 @@ config TARGET_SOCFPGA_GEN5
>>   	bool
>>   	select SPL_ALTERA_SDRAM
>>   	imply FPGA_SOCFPGA
>> +	imply SPL_SIZE_LIMIT_SUBTRACT_GD
>> +	imply SPL_SIZE_LIMIT_SUBTRACT_MALLOC
>>   	imply SPL_STACK_R
>>   	imply SPL_SYS_MALLOC_SIMPLE
>>   	imply USE_TINY_PRINTF
>>
> 512 bytes for stack looks like it's too little. I think the SPL started
> misbehaving when it overgrew 50 kiB, no ?

To 1: Well, I tested the stack usage once, booting from eMMC, and was 
somewhere below that range. But yes, it's a problem for the future: once 
we get a more stack-consuming function, we might be lost. Which size 
would you suggest?

To 2: No. The documentation says 60 KiB would be the limit (upper 4 KiB 
reserved for BootRom usage while loading SPL). I'm running SPL with the 
DM_CLK driver (still under development) with a binary (code + dtb) of 
about 58 KiB and it runs fine. Heap size before relocation increases to 
around 4KiB though, so that ensures the 60 KiB limit isn't breached.

Regards,
Simon