Need help howto boot imx28 from USB stick?

[iMxGuy]

Hi, I would like to be able to boot the i.MX28 EVK board from a USB stick but I could not find the documentation on how to setup the USB stick to do this. When I plug in the USB stick, the demo Linux image on the SD card does not even see the USB device. Can anyone point me to some documentation or post a reply on how to do it?

[VladanJovanovic]

It is not possible to boot directly from USB memory stick. You are able to program a blank device via USB though using a PC-based tool (like the Manufacturing Tool for example).

You could organize your boot so that linux kernel is started from small SPI flash which would then mount the root file system from USB stick and continue booting from there...

Vladan

[AhmetYUCE]

One more point, perhaps kernel have mass storage support but udev or mdev (whichever being used in demo image) doesn't have rules for creating device nodes on the fly. So first check if correct device node is created, then you can issue a "mount" command. Regards Ahmet

[iMxGuy]

Thanks for the explanation on USB booting. I saw in the documentation about booting from USB and I assumed you could do it as a mass storage device. The documentation is not very clear on what they mean by USB booting, but it looks like it is only supported in Windows as I did not see any mention of Linux in the docs.

As far as mounting the USB stick on the EVK, I do see the USB core is loading in the kernel so I think the stock demo SD card has support for USB but maybe not the mass storage device driver or the FAT file system. I will have to look into it more. Thanks.

[AhmetYUCE]

Probably it's not possible to boot from USB stick directly. To be able to do this, embedded boot program in iMX28 should run a host mode USB, then mount usb stick, and read FAT or NTFS file system of USB stick. Finally read the .sb files from it. I think there is no such support in embedded boot program, it's HIS class, device mode only. Check out chapter 12 of reference manual. Practically you can boot from nand flash, sd card and serial flash. Or upload files into SDRAM via USB. Regarding the demo linux image, if the neccessary options are selected in kernel you should see some messages on console. After manually mounting the disk you should be able to access it's contents. Since i didn't use stock kernel since the begining, I'm not sure if USB memory access options are selected on demo kernel, bu i guess it is. Regards Ahmet