On 12/21/09 19:30, Somebody in the thread at some point said:
Hi -
Let me add back the context for this quote:
''While working at Openmoko maintaining their kernel, it became obvious
that U-Boot was turning into a mini-me for Linux. Many cut-down Linux
drivers were appearing there, there was a shell with an environment
holding private states ...''
Another big problem with U-Boot was the inability to update the
bootloader from the Linux world. Instead the bootloader was treated
special and had to be updated over USB with DFU (the exclusivity of it
enforced by an ECC policy disconnected from Linux, meaning U-Boot had to
write it in there). In Qi, the bootloader can be updated by a packaged
update like anything else in the rootfs.
Can you explain to me why it was not possible to update U-Boot from
Linux? I cannot imagine a reason for such a restriction.
I was talking about GTA02 specifically here, it was (and still is AFAIK)
only updateable by DFU for the bootloader. We had kernels with soft ECC
that differed from the ECC / bad block marking generated and used by the
s3c2442 NAND hardware unit. If U-Boot wrote it, it could at least read
it again. So DFU was / is the only official way to update GTA02 bootloader.
As you say nothing generally stops update of U-Boot from Linux same as
anything else can be updated from there, if Linux can write those NAND
sectors with ECC / BBT that the bootloader can understand or ignore, and
Linux can understand and comply with / update the BBT scheme of U-Boot.
Another benefit of SD Card boot is that it regularizes the bootloader
physical storage, so these issues don't exist and it can always be
updated from Linux.
-Andy
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