subject:"Re\: \[U\-Boot\] \[PATCH sunxi\-tools\] WIP\: fel\: Add a command for loading U\-Boot SPL binaries in eGON format"

Re: [U-Boot] [PATCH sunxi-tools] WIP: fel: Add a command for loading U-Boot SPL binaries in eGON format

2015-02-08 Thread Siarhei Siamashka

On Sat, 07 Feb 2015 10:21:46 +0100
Hans de Goede hdego...@redhat.com wrote:

Hi,

On 02/07/2015 04:17 AM, Siarhei Siamashka wrote:
On Thu, 5 Feb 2015 22:49:39 -0700
Simon Glass s...@chromium.org wrote:

Hi Siarhei,

On 5 February 2015 at 02:36, Siarhei Siamashka
siarhei.siamas...@gmail.com wrote:
!!! Works only on Allwinner A20 so far and needs a bit more
!!! debugging. And even on A20, the transition from the SPL to
!!! the main U-boot binary has some glitches.

Now it should be possible to load and execute the same U-Boot SPL,
as used for booting from SD cards. The only argument for this new
command is the name of the SPL binary file (with eGON header).
It can be run as:

fel spl u-boot-sunxi-with-spl.bin

This looks great! Does it write only the SPL portion or does it write
U-Boot also?

Yes, it only takes care of the SPL part at the moment, but surely
this can be improved later.

The biggest inconvenience is that we need to provide the 'fel' tool
with with the magic address for the main u-boot binary. This address
is hidden in the u-boot sources:

http://git.denx.de/?p=u-boot.git;a=blob;f=include/configs/sunxi-common.h;h=6cfd7e148900#l28

But the users need to know it in order to set in as the command
line argument for the 'fel' tool.

We could probably do a better job and store the necessary addresses
in the SPL header. Currently 'mksunxiboot' provides only a
minimalistic header with the eGON.BT0 signature and a checksum,
because otherwise it will refuse to boot from the SD card:

http://git.denx.de/?p=u-boot.git;a=blob;f=tools/mksunxiboot.c

But probably we can extend this header and also add the
CONFIG_SYS_TEXT_BASE value there. Together with kernel_addr_r,
fdt_addr_r, scriptaddr and ramdisk_addr_r values.
After this change, the 'fel' tool will be able to extract all
the necessary information from u-boot-sunxi-with-spl.bin
file without relying on the command line too much.
Moreover, these addresses are sometimes changing, and some
users are IMHO rightfully upset whenever this happens:

I think that adding a new header for this sounds like a good idea, this
header should start with some 8 byte magic marker so that the fel tool
can be 100% sure if it is there.

http://permalink.gmane.org/gmane.comp.hardware.netbook.arm.sunxi/14919

I don't really understand how it works but will leave that to you and Hans.

OK :) Anyway, now I have finally pushed a supposedly properly working
implementation to the following github branch:

https://github.com/ssvb/sunxi-tools/commits/20150206-fel-large-spl-support

Cool (note I've not looked at the actual code yet), this all sounds quite
nice.

It would be really cool if when the new header is present and with a new
enough fel tool + u-boot bin we could do:

That's the (longer term) plan.

fel spl u-boot-sunxi-with-spl.bin zImage - dtb

or:

fel spl u-boot-sunxi-with-spl.bin zImage initrd dtb

And everything would just work, note that the zImage initrd dtb order
is the same as u-boot's bootm command, and the - is there to indicate
there is no initrd.

I would perhaps prefer to keep the current 'spl' command name just for
the SPL alone. And invent some new name for a more advanced command to
use it with the future u-boot v2015.07 release.

Maybe we should also do something for old kernels where script.bin needs
to be loaded, maybe:

fel spl-old-kernel ... ??

Isn't the script.bin normally loaded exactly at the same address
as the dtb? So nothing special is really needed for old kernels here.

Yes, we can handle most of this stuff with Hans. But some communication
with you is still needed. In particular, we still need to decide a way
to distinguish between booting from the SD card and over USB. Your
RFC/WIP patch from
http://lists.denx.de/pipermail/u-boot/2015-February/203858.html
was checking the value in the 'lr' register, but this is not going to
work anymore. To address this, right now I'm just replacing the
eGON.BT0 signature in memory to a new eGON.FEL signature at the
address 0x0004. The idea is that this signature is critical for booting
from the SD card. If there is some other value instead, then we are
pretty sure that the SPL was not booted from the SD card. And having it
as eGON.FEL serves as an indication of what exactly it is.

I think that replacing eGON.BT0 with eGON.FEL when loading the SPL
through the new mode is a good way of doing this, ACK to that.

Additionally, we might even not need to store the lr and sp
registers in save_boot_params(). If we settle on using the eGON.FEL
signature in memory for distinguishing between the FEL and the SD boot,
then we can also reuse the other parts of of header (for example,
the checksum) to store the return address.

We'll have to see how this all works out to determine whether or not that
is a good idea.

Re: [U-Boot] [PATCH sunxi-tools] WIP: fel: Add a command for loading U-Boot SPL binaries in eGON format

2015-02-07 Thread Hans de Goede