MMC prepare for zynq

[Johannes Roith]

Hi Gwenhael, hi Ahmad

Am Fri, Jul 04, 2025 at 04:56:01PM +0200 schrieb Ahmad Fatoum:
> Hi Gwenhael,
> 
> On 7/3/25 09:18, Gwenhael Goavec-Merou wrote:
> > Dear all,
> > 
> > I'm trying to uses my zedboard with barebox but can't be able to boot this.
> > 
> > According to mails found in this mailing list I have done this sequence:
> > 
> > export ARCH=arm
> > export CROSS_COMPILE=$SOMEWHERE/arm-buildroot-linux-gnueabihf-
> > 
> > make zynq_defconfig
> > make -j$(nproc)
> 
> That looks correct IMO.
> 
> > And copied in the first SDCard FAT partition:
> > - images/barebox-avnet-zedboard.img as BOOT.bin
> > - barebox.bin
> 
> Which binary is barebox.bin?

The first one is the correct one. Just copy the images/barebox-avnet-zedboard.img
with the name BOOT.bin to an SD-Card whose first partition is FAT32.
> 
> > But I have nothing displayed through serial port.
> 
> Two things come to mind:
> 
> - The Image is 184K. Does the Zynq enforce a maximum limit on the BOOT.BIN?

Yes, there is a limitation for the size of the First Stage Bootloader
(FSBL) as Xilinx calls it, which is the available SRAM size in the ZYNQ
7000 (192 kBytes). Currently Barebox PBL and Barebox Proper are combined
to one image (images/barebox-avnet-zedboard.img) but you will get an
error in the build process, if your image exceeds this size.
> 
> - Does DEBUG_LL produce any output? For details on how to configure
> DEBUG_LL, see the troubleshooting guide I just Cc'd you on.
> 
> > Are there somewhere details on how to prepare SD Card for a zynq board?
> 
> I haven't done work with the Zynq 7000 so far, but Lucas and Johannes
> did. I Cc'd them as they may be able to give some tips for troubleshooting.

I would also take a look at this message on the mailing list:

https://lore.barebox.org/barebox/DB7PR02MB43323CD77E0507E560475BCAABF00@DB7PR02MB4332.eurprd02.prod.outlook.com/

Here, the content of the file
arch/arm/boards/avnet-zedboard/zedboard.zynqcfg caused a boot error for
barebox. With my Digilent Cora Z7 board, I also had to modify the file
by deleting everything but the last line, to get barebox booting. Have
you already tried this?

> 
> Cheers,
> Ahmad
> 
> > 
> > Thanks
> > 
> > Gwenhael
> > 
> > 
> 
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Best regards,
Johannes