[U-Boot] [PATCH v2] MIPS: start.S: unify and simplify reset vector handling

[Langer Thomas (LQDE RD ST PON SW)]

Hello Daniel,

Daniel Schwierzeck wrote on 2013-02-01:

> 2013/2/1 Gabor Juhos <juhosg at openwrt.org>:
>> Hi Daniel,
>> 
>>> From: Daniel Schwierzeck <daniel.schwierzeck at gmail.com>
>>> 
>>> Adopt reset vector handling from Yamon.
>>> 
>>> Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck at gmail.com>
>> 
>> Looks good, I have only one minor comment below.
>> 
>>> ---
>>> Changes for v2:
>>> - optimized U-Boot entry point on MIPS32
>>> - fix indentation of .org
>>> 
>>> ---
>>>  arch/mips/cpu/mips32/start.S | 186 +++++++++----------------------------------
>>>  arch/mips/cpu/mips64/start.S |  47 +++++------
>>>  2 files changed, 57 insertions(+), 176 deletions(-)
>>> diff --git a/arch/mips/cpu/mips32/start.S b/arch/mips/cpu/mips32/start.S
>>> index 65acf7d..7373d4e 100644
>>> --- a/arch/mips/cpu/mips32/start.S
>>> +++ b/arch/mips/cpu/mips32/start.S
>>> @@ -47,19 +47,16 @@
>>>       .set    pop
>>>       .endm
>>> -#define RVECENT(f,n) \
>>> -   b f; nop
>>> -#define XVECENT(f,bev) \
>>> -   b f     ;           \
>>> -   li k0,bev
>>> -
>>>       .set noreorder
>>>       
>>>       .globl _start
>>>       .text
>>>  _start:
>>> -     RVECENT(reset,0)                        # U-boot entry point
>>> -     RVECENT(reset,1)                        # software reboot
>>> +     /* U-boot entry point */
>>> +     b       reset
>>> +      nop
>>> +
>>> +     .org 0x10
>>>  #ifdef CONFIG_SYS_XWAY_EBU_BOOTCFG
>> 
>> The .org should be within the ifdef. Although it does not change the
>> generated binary code, but logically it would be a more correct place.
>> Sorry, I should have mentioned that in the previous mail.
>> 
>> -Gabor
>> 
>> 
> 
> I think we should keep it outside. If we add qemu-malta, then we get
> another #if branch.
> I also would like to move some register inits (watch, timer, status)
> to slightly reduce
> binary size.
>
In addition you could completely remove these exception vectors for u-boot binaries,
which will be loaded from SPI- or NAND-flash (or some other storage, which is not
memory mapped), which typically involves some ROM code.
In this case, the vectors are already part of the ROM.

Best Regards,
Thomas