[U-Boot-Users] passing bootargs to Linux on NIOS

[U-Boot-Users] passing bootargs to Linux on NIOS

[Thomas Brand]

Hi,

I'm currently implementing the bootm command for the NIOS processor from 
Altera. I'd like to pass boot arguments to the kernel. I tried to figure 
  out how it works in other architectures, but I'm still clueless.

I call the function theKernel(...) with some arguments like I have seen 
it in other implementations. Now my question is, how do I access these 
arguments in the kernel?. I know the NIOS processor is passing the first 
4 arguments in registers when calling a function as a subroutine. But in 
the linux kernel in main.c is another call in the function 
start_kernel() for a kernel specific setup [setup_arch()] which will 
move the window-pointer and so change the registerfile. Therefore I 
cannot access the registers directly.

Or should I just define a piece of memory to put the arguments in? It 
will be hard coded in the kernel then.

Any hints? Every answer will be appreciated.

Thomas

[U-Boot-Users] passing bootargs to Linux on NIOS

[Wolfgang Denk]

In message <41120FD7.9070002@imms.de> you wrote:
> 
> I'm currently implementing the bootm command for the NIOS processor from 
> Altera. I'd like to pass boot arguments to the kernel. I tried to figure 
>   out how it works in other architectures, but I'm still clueless.

What exactly don't you understand? 

> I call the function theKernel(...) with some arguments like I have seen 
> it in other implementations. Now my question is, how do I access these 
> arguments in the kernel?. I know the NIOS processor is passing the first 

Well, how does the NIOS version of the kernel access it's boot arguments?

> 4 arguments in registers when calling a function as a subroutine. But in 
> the linux kernel in main.c is another call in the function 

main.c is not the right place to look. You want to check the kernel's
entry point, i. e. "_start" (there is probably some "head.S"  file  n
your source tree?).

> Or should I just define a piece of memory to put the arguments in? It 
> will be hard coded in the kernel then.

You design it...


Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
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