Re: [9front] PXE booting Rpi

[Daniel Morandini <danielmorandini@me.com>]

Good morning cinap!

> ok, i just tried the 32 bit pi2 kernel with a raspberry pi 3B+ 
> pxeboot and the R2 register appears to be zero on entry.
I stumbled upon the R2 thing just by reading the docs and as I was
debugging my issue I thought the docs/comments mismatch might have
been an hint.

I did not double-check it as:
- I don't know yet how to access a register (:D) (is KADDR giving a 
pointer to it? What if I give it 2 instead of 0?), and 
- I assumed `if(pa != 0 && /* smth */` is never asserted as pa is
apparently always 0.

If I call bootargsinit(2) which calls KADDR(2) is yielding R2, I just
checked it and (without device_tree= in config.txt, otherwise the
fallback works and the Pi loads the args) the Pi is *NOT* loading
neither devtree nor atags: I assume you’re right then? No R2 for
Pis?

I’ll be on it later this afternoon.

Why the ‘pa != 0’ check?

---

Mine is a Raspberry Pi 2 Model B V1.1 (BCM2836)!
> this is with the latest bootcode.bin and start_cd*.elf:
> 
> term% sha1sum bootcode.bin fixup_cd.dat start_cd.elf
> 76b71ff97ace39d9900c27f761f7548c4c6f49a5	bootcode.bin
> 1585386a20cfc42b541f3ed1439d90e8c5b4529e	fixup_cd.dat
> e08d5b453ad1203f85cc5421b96ed6ebcc2f2299	start_cd.elf
filefucker# sha1sum bootcode.bin start_cd.elf fixup_cd.dat
0f3e37fdc441fcb20fbd746978e05386acfdf876	bootcode.bin
b2af5034d792c5baaa6a8897f9ac24d308e66026	start_cd.elf
72522c2c4bc18d7bea76c40a6b4330cd0f2bd52a	fixup_cd.dat

Apparently we’re using different stuff :D

> and the following settings in config.txt:
> 
> [pi3]
> kernel=../../sys/src/9/bcm/9pi2
> 
> [all]
> gpu_mem=16
> enable_uart=1
> boot_delay=1
Mine is:
kernel=9pi2
device_tree=
gpu_mem=16
enable_uart=1
uart_2ndstage=1

> note that atags worked just fine for me, without any
> special setting.
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!

Cheers,
dan