Re: [9fans] ARM and u-boot

[Steven Stallion <sstallion@gmail.com>]

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On Sat, Jun 1, 2013 at 12:19 AM, <tlaronde@polynum.com> wrote:

> Since it has u-boot installed and that the mapping of the flash is given
> does one know if one could build a Plan9 kernel, write it (via
> u-boot) to the flash and be able to boot?
>

It's quite possible. I even have it working. :-)

A couple of months ago I submitted a patch to the U-Boot mainline to add
formal support for Plan 9 kernels. It has since been accepted. At the same
time I also submitted a patch to Geoff which has been gathering dust to add
uImage support to 5l (patch/arm-uboot) - a requirement to exist nicely with
the loader. The exynos5 port that I am working on (Arndale Board, Samsung
Chromebook) relies on this exclusively.

If you are familiar with setting up a BSP for U-Boot, it's fairly
straightforward to boot a Plan 9 kernel from either a filesystem (ie. FAT,
ext2, etc.) or via TFTP. I tend to use TFTP while testing new kernels,
though longer lived kernels will likely end up sitting in a FAT - I haven't
quite decided yet.

Since you seem to be keen console spew, this is what a booted Arndale looks
like with the above patches:

U-Boot 2013.01.-rc1-00002-g67fd7e7-dirty (May 10 2013 - 23:58:01) for
ARNDALE5250

CPU: Exynos5250@1000MHz

Board:  for ARNDALE5250
I2C:   ready
DRAM:  2 GiB
WARNING: Caches not enabled

Checking Boot Mode ... SDMMC
MMC:   EXYNOS DWMMC: 0, EXYNOS DWMMC: 1, EXYNOS DWMMC: 2
In:    serial
Out:   serial
Err:   serial
Net:   No ethernet found.
(Re)start USB...
USB0:   USB EHCI 1.00
scanning bus 0 for devices... 4 USB Device(s) found
       scanning usb for storage devices... 0 Storage Device(s) found
       scanning usb for ethernet devices... 1 Ethernet Device(s) found
Hit any key to stop autoboot:  0
Waiting for Ethernet connection... done.
Using asx0 device
TFTP from server 10.0.0.8; our IP address is 10.0.0.10
Filename '/sys/src/9/exynos/9arndale'.
Load address: 0x42000000
Loading: #################################################################
 ###############################################
done
Bytes transferred = 1510728 (170d48 hex)
## Booting kernel from Legacy Image at 42000000 ...
   Image Name:   9arndale
   Image Type:   ARM Plan 9 Kernel Image (uncompressed)
   Data Size:    1510664 Bytes = 1.4 MiB
   Load Address: b1000000
   Entry Point:  b1000000
   Verifying Checksum ... OK
   Loading Kernel Image ... OK
OK
## Transferring control to Plan 9 (at address b1000000) ...

Plan 9 from Bell Labs
...

Cheers,

Steve

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