[PATCH 05/10] powerpc: mpc8xx: Reorganise init RAM

[Christophe Leroy]

Le 04/05/2023 à 12:07, Joakim Tjernlund a écrit :
> On Thu, 2023-05-04 at 10:56 +0200, Christophe Leroy wrote:
>> Using SMC relocation microcode patch or USB-SOF microcode patch
>> will disable DPRAM memory from 0x2000 to 0x2400 and from 0x2f00
>> to 0x3000.
>>
>> At the time being, init RAM is setup to use 0x2800-0x2e00, but
>> the stack pointer goes beyond 0x2800 and even beyond 0x2400.
>>
>> For the time being we are not going to use any microcode patch
>> that uses memory about 0x3000, so reorganise setup to use:
>> - 0x2800 - 0x2e00 for init malloc and global data and CPM buffers
>> - 0x3000 - 0x3c00 for init stack
>>
>> For more details about CPM dual port ram, see
>> commit b1d62424cb ("powerpc: mpc8xx: redistribute data in CPM dpram")
>>
>> Signed-off-by: Christophe Leroy <christophe.leroy at csgroup.eu>
>> ---
>>   arch/powerpc/cpu/mpc8xx/start.S    |  9 +++++----
>>   arch/powerpc/include/asm/cpm_8xx.h | 16 ++++++++--------
>>   include/configs/cmpc885.h          |  1 +
>>   include/configs/mcr3000.h          |  1 +
>>   4 files changed, 15 insertions(+), 12 deletions(-)
>>
>> diff --git a/arch/powerpc/cpu/mpc8xx/start.S b/arch/powerpc/cpu/mpc8xx/start.S
>> index 0aa73fca12..41f12021c8 100644
>> --- a/arch/powerpc/cpu/mpc8xx/start.S
>> +++ b/arch/powerpc/cpu/mpc8xx/start.S
>> @@ -141,14 +141,15 @@ in_flash:
>>   	mtspr	DER, r2
>>   
>>   	/* set up the stack on top of internal DPRAM */
>> +	lis	r1, CFG_SYS_INIT_SP at h
>> +	ori	r1, r1, CFG_SYS_INIT_SP at l
>> +	stwu	r0, -4(r1)
>> +	stwu	r0, -4(r1)
> 
> Changing stack ptr incrementally is likely to confuse gdb which may do stack accesses if you single step
> over this code. It is better to setup the stack in a different reg and the just assign r1 when done.
> 

Ok, I can change that. But we are at the very begining and r1 is 
undefined until now so it shouldn't matter.

Christophe