[meta-xilinx] FSBL.elf and BOOT.BIN using bitbake and SDCard booting

[Nathan Rossi]

On Tue, Oct 11, 2016 at 12:15 PM, Giordon Stark <kratsg at gmail.com> wrote:
> Thanks, some elaboration below!
>
> On Mon, Oct 10, 2016 at 8:58 PM Nathan Rossi <nathan at nathanrossi.com> wrote:
>>
>> On Tue, Oct 11, 2016 at 9:49 AM, Giordon Stark <kratsg at gmail.com> wrote:
>>
>> > Hi,
>>
>> >
>>
>> > I am using bitbake to build on top of a custom machine [eg: using my
>>
>> > devicetree] and then generating the following files which I renamed into
>> > a
>>
>> > format appropriate for meta-xilinx
>>
>> >
>>
>> > -rwxr-xr-x 1 kratsg  59K Oct  5 17:31 BOOT.BIN
>>
>> > -rw-r--r-- 1 kratsg  22K Oct  5 17:30 devicetree.dtb
>>
>> > -rw-r--r-- 1 kratsg 3.2M Oct  5 17:30 uImage
>>
>> > -rw-r--r-- 1 kratsg  26M Oct  5 17:15 uramdisk.image.gz
>>
>> > -rwxr-xr-x 1 kratsg 2.4M Oct  5 17:30 u-boot.elf
>>
>> >
>>
>> > The machine is defined here:
>>
>> >
>> > https://github.com/kratsg/meta-l1calo/blob/master/conf/machine/gfex-prototype2.conf
>>
>> >
>>
>> > The image I make (bitbake zynq-base) is defined here:
>>
>> >
>> > https://github.com/kratsg/meta-l1calo/blob/master/recipes-core/images/zynq-base.bb
>>
>> >
>>
>> > So i'm hoping this is relatively straightforward. Now I get a little
>>
>> > confused about actually booting this on the board using the SD Card.
>>
>> > According to the docs
>>
>> > (https://github.com/Xilinx/meta-xilinx/blob/master/docs/BOOT.sdcard) it
>>
>> > seems that I need to only use four files generated from bitbake:
>>
>> > devicetree.dtb, uImage, uramdisk.image.gz, and u-boot.elf; and then use
>> > the
>>
>> > Xilinx SDK to create an FSBL.elf, use the u-boot.elf from bitbake, and
>>
>> > create a boot image (BOOT.BIN). Why isn't this able to be done using
>>
>> > bitbake? When I try everything without using the Xilinx SDK, I see the
>> > error
>>
>> > message [1].
>>
>>
>>
>> Those docs are a bit old, for the last release I re-wrote the
>>
>> documentation as README.booting.md in the root of meta-xilinx.
>>
>>
>>
>>
>> https://github.com/Xilinx/meta-xilinx/blob/master/README.booting.md#loading-via-sd
>>
>>
>
> Awesome, I was not aware that the docs were rewritten. I didn't even realize
> there was a README.booting.md at the top level. Perhaps that can be
> clarified somewhere?

It is mentioned in the README, maybe removing the old docs will remove
any confusion?

>
>>
>>
>> Also I am not sure about your question regarding boot.bin generation.
>>
>> But if you machine provides the ps7_init_gpl* files (your machine is
>>
>> including zc706, so they are available) it is able to build u-boot-spl
>>
>> (which does the same job as FSBL) and wrap that in the boot.bin format
>>
>> for use. If you need FSBL specifically then that is a separate issue.
>
>
> For right now, we are using a custom board with a ZC706. We'll move to the
> Zynq+ in the next generation (as well as bump up versions of everything from
> Jethro). So I imagine we will always have these ps7_init_gpl available (I
> imagine you refer to these:
> https://github.com/Xilinx/meta-xilinx/tree/master/recipes-bsp/platform-init/platform-init/picozed-zynq7).

So ZynqMP is a bit different, there is U-Boot SPL support. However
this is not exposed yet in meta-xilinx, but will be in the future.

The directory you linked has the ps7_init_gpl* files which are
specific for the picozed board. The platform-init recipe though would
be one of the ways you can supply the ps7_init for your machine should
you need to. For zc706 the ps7_init_gpl* files are actually in the
U-Boot source tree
(http://git.denx.de/?p=u-boot.git;a=tree;f=board/xilinx/zynq;h=2fc205e4e97071b73a16c00dec1d6804e418343f;hb=HEAD).

>
> I do not totally understand how/why this can replace the FSBL entirely?
> http://www.wiki.xilinx.com/U-Boot+Secondary+Program+Loader#Task%20Description-Build%20U-Boot%20SPL
> seems to indicate it is not fully supported by Xilinx. In fact, I never
> understood how the FSBL normally worked because I understood the process as
> ROM Code -> SPL -> U-BOOT -> Kernel.

That is the boot flow yes. And correct it is not "supported" by
Xilinx, so you cannot expect to contact Xilinx support channels with
regards to SPL. But support for SPL is definitely available in the
community whether it be here on meta-xilinx or with U-Boot itself.

FSBL is actually not a very complex program, all of the complex
register initialization done for DDR, PLL, etc setup is actually
contained in the ps7_init_gpl* code files generated by Vivado (in the
HDF).

If you are interested you can actually see the source for FSBL here
https://github.com/Xilinx/embeddedsw/tree/master/lib/sw_apps/zynq_fsbl/src.
However it is important to note that FSBL is licensed under a
restrictive Xilinx only use license.

>
> We do not necessarily require FSBL so this is fine. Looking at the files
> generated (https://gist.github.com/kratsg/ba23d69a84db769cf8183b3dbc37c2f3)
> with my attached local.conf there -- I do not see this. I'm guessing this is
> in a later release of poky. I can certainly update later to move to this
> workflow soon... unless you suggest I do it now over FSBL?

Not sure what you mean by "I do not see this". I believe you might be
confused as to what the boot.bin file is that is produced from the
meta-xilinx build. This is actually u-boot-spl packed into a boot.bin
for booting on Zynq. See my comment below where you are querying how
it is booting.

>
>>
>>
>>
>>
>> >
>>
>> > My second (less important) question is how to get bitbake to generate
>> > the
>>
>> > filesystem in the right format? Right now, I have to run
>>
>> >
>>
>> > mkimage -A arm -T ramdisk -C gzip -d
>>
>> > zynq-base-gfex-prototype2.cpio.gz.u-boot uramdisk.image.gz
>>
>>
>>
>> *.cpio.gz.u-boot == uramdisk.image.gz. They are the same format
>>
>> (except that i think the default Xilinx images are "ext.gz.u-boot"),
>>
>> so there is no need to double wrap the ramdisk with two u-boot mkimage
>>
>> headers :).
>
>
> The default appears to be cpio.gz.u-boot. If I didn't wrap it this way, I
> could not get the filesystem loaded using that file. It needed the mkimage
> command.

Interesting, could you provide the commands/setup you are using in
U-Boot to load the ramdisk? Because it should be able to load the
cpio.gz.u-boot file directly from the bootm command.

>
>>
>>
>>
>>
>> >
>>
>> > in order to get the correct uramdisk.image.gz . Is there a way to make
>>
>> > bitbake generate the right image so I don't need to run this command so
>> > that
>>
>> > u-boot understands my image when booting?
>>
>> >
>>
>> > Giordon
>>
>> >
>>
>> > [1]
>>
>> > U-Boot SPL 2015.04 (Oct 05 2016 - 13:12:31)
>>
>>
>>
>> It looks like you are using the jethro version of OE/meta-xilinx? If
>>
>> so, the new documentation might not exactly match the process (e.g.
>>
>> "u-boot-dtb.img" instead of "u-boot.img").
>
>
> Noted. I do have u-boot-dtb.img instead of u-boot.img
>
>>
>>
>>
>>
>> > mmc boot
>>
>> > reading fpga.bin
>>
>> > spl_load_image_fat: error reading image fpga.bin, err - -1
>>
>> > spl: error reading image fpga.bin, err - 1
>>
>> > reading system.dtb
>>
>> > spl_load_image_fat_os: error reading image system.dtb, err - -1
>>
>> > reading u-boot-dtb.img
>>
>> > spl_load_image_fat: error reading image u-boot-dtb.img, err - -1
>>
>> > ### ERROR ### Please RESET the board ###
>>
>>
>>
>> If you follow the documentation I linked above it will mentioned
>>
>> adding the "u-boot-dtb.img" file to your SD card. This is what you are
>>
>> missing here, which is why you get the error.
>
>
> Really? But as it stands, there is no FSBL or SPL in my list of files. So
> how is it able to boot otherwise?

Right so the default build of meta-xilinx will produce a "boot.bin"
file. This is the boot.bin file you have loaded on your target.

Currently the only boot.bin that meta-xilinx can produce is one which
has U-Boot SPL packed into it. Note the log message you are getting on
boot that says "U-Boot SPL 2015.04...".

Regards,
Nathan

>
>>
>>
>>
>>
>> Regards,
>>
>> Nathan
>>
>>
>>
>> >
>>
>> >
>>
>> > --
>>
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>>
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>>
>