Op vrijdag 12 september 2014 19:16:46 UTC+2 schreef RobertCNelson:
>
> On Fri, Sep 12, 2014 at 5:14 AM, <[email protected] <javascript:>>
> wrote:
> > Hello,
> >
> > I'm new here, so I'll introduce myself, I'm an embedded software
> developer
> > working with ARM based boards (A10, iMx, AM335x) from the Netherlands.
> >
> > I've been working on a custom linux installation for the BBB
> (buildroot).
> > There's only one nagging problem I can't seem to solve. For booting I
> use
> > u-boot and an uSD card with three partitions. The first is FAT. This
> work
> > fine. But then comes the problem: eMMC.
> >
> > It seems like the only way to let the BBB boot off the eMMC is to create
> a
> > FAT partition (#1) that goes from cylinder 1 to 9 (255 heads, 63
> sectors).
> > The eMMC is big enough for sure, so that's no problem, but it bothers me
> > that I can't seem to change the partition size, and I don't understand
> why.
>
> That's an old requirement, it was a "x-loader" bug, that got fixed
> years ago.. (x-loader (original MLO) couldn't find "u-boot.bin")
>
>
Thing is, MLO isn't even loaded, I just get the CCCC console output.
>
> > On the partition is a vfat filesystem with the MLO, u-boot.img and
> uEnv.txt
> > files.
> >
> > I've read the AM335x technical reference thoroughly, checked all the
> boot
> > flowcharts against a hexdump of the mmcblk1 device, but I can't find the
> > reason why the device won't boot when I change the partition size.
> >
> > Does anyone know about any requirements I've missed? Is the size a given
> > constraint? I would like to use a very small FAT partition of 1MB or
> so..
>
> fat16 needs 12MB or greater to work.
>
> I din't realize that.. I have a 1MB FAT32 partition on the uSD card that
works just fine..
So I reasoned that this should work on the eMMC too.,.
> btw, instead of bothering with the fat partition, just use one big ext4:
>
> sudo dd if=MLO of=/dev/sdX count=1 seek=1 conv=notrunc bs=128k
> sudo dd if=u-boot.img of=/dev/sdX count=2 seek=1 conv=notrunc bs=384k
>
> Then just remember, to create the first partition with a 1mb hole at the
> start.
>
> sudo sfdisk --in-order --Linux --unit M ${DISK} <<-__EOF__
> 1,,0x83,*
> __EOF__
>
> This is a good solution, thank you. It still bothers me that I can't get a
handle
on why the FAT booting *only* works with a single specific partition size,
but
I'll let it go :)
Best regards,
Sjef.
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