Hi Marek,
Hey, this looks reasonable. Did you send similar patch to Linux too ?
No, I'm not at that yet. I'm just starting to explore the New U-Boot: It's been since version 1.1.2 that I have actually contributed something.
My current project requires a mechanism to manipulate GPIO pins, to aid the bring-up of a new board in a couple of weeks. Until last weeks I've been using the ancient FreeScale supplied U-Boot. When I took that in, your work didn't appear in the repository yet, so finding that was a big and pleasant surprise. Especially because the FreeScale version had a couple of bugs in it. Not to start about the bugs in the supplied bootlets...
So taking in U-Boot with your work is killing at least 3 birds with one stone.
I will do some work on the Kernel later. For now we're using the FreeScale supplied Kernel. I have tried 3.1rc4 before and it ran our application perfectly, so that's looking good already. But changing Kernel 2 weeks before board bring-up is a bit too exciting for me. For that reason I will probably hold on to the FreeScale bootlets and U-Boot version too.
But now I've got your attention anyway: Is there a reason why U-Boot expects the bootstream at sector 1024 of the SD-Card?
To make things simple for users, there's standard layout. It's actually at sector 2048 btw.
The internal bootrom doesn't know this limitation. It is clever enough to interpret the partition table, and start loading SRAM from the first sector of the first partition of type 53.
That's what happens internally, it's just that some pieces (like sector offset of the partition!) need to be filled into the bootstream header by the mxsboot utility -- see mxsboot -h for how to change that.
The 2048 sector offset was chosen because that's standard in Linux now for first partiiton.
Now I figure that the internal bootrom can only load the first part of U-Boot, because of SRAM limits, and that this first part has to power-up all power rails, initialize SD-RAM and load the remainder of U-Boot, but I don't see why it couldn't be as clever as the internal bootrom.
What do you mean?
The reason I'm asking is because our project intends to boot from MMC all the time. We don't think unmanaged NAND is reliable enough for our appliction. We would like to have the oppertunity to boot from an SD-Card, that also usable on Windows. And since that poor OS doesn't know the difference between a disk, a partition and a file system it gets confused if the first partition on an SD-Card isn't FAT formatted.
You can adjust that, see above.
Cheers,
Robert.