Re: [9front] PXE booting Rpi

[Daniel Morandini <danielmorandini@me.com>]

> nonono. you have to save the R2 register on entry and get it to
> main. see the diff later.
> 
> nononono. KADDR() translates a physical address to the KZERO window
> of the kernel. like physical address 0 becomes (KZERO+0)... this
> for accessing memory (reading the DTB/ATAGS).
Sorry for these stupid questions, the code really is self explanatory

> i already said that bootargs.c in bcm/ is shared also by the bcm64
> kernel, where we pass the dtb pointer to it. but it is not used in
> the 32 bit bcm kernel. that is why there is a conditional. a pa
> of 0 means the address is not valid. its like a NULL check.

> theres also a special case that ATAGS are trashed on kernel-to-kernel
> reboot. so even on bcm64, pa can be 0 when the information has been
> converted to CONFADDR text block.
All clear now.

>> Just to learn something from a master, how are you debugging this?
>> I’m collecting data and dumping it as soon as print is ready!
> 
> thats pretty much how you do it.
> 
> anyway, heres how i checked what R2 is on entry. basically,
> move R2 to R10 (which is reserved by c code for the mach
> pointer so c code wont trash it). and then before calling
> main() put it in R0 (first arument).
This is so cool cinap, thank you for sharing! *.*

With patch attached and a `bootargsinit(arg0)` instead of 0 that’s
it, issue solved without `device_tree=` option! The fw loads a dtree
and we correctly load it from the proper address!

Cheers,
dan