Yes, I have read it, but it doesn't really answer my question. I'm not asking if I can boot from RAM, I'm asking why would someone think it could be done? If anything, 14.2.1 re-inforces my point: if booting from RAM doesn't make sense, why are so many board header files configured to enable it?
Ok, I don't want to be flamed here ... but I can think of a potential method of booting to RAM ... but whether or not it is considered useful in the context of U-Boot is debatable.
The MPC8349E can be booted such that the core is held in reset, and the processor registers can be configured over PCI by another host computer. Therefore it is conceivable that the host can program the SDRAM controller on the MPC8349E and take the core out of reset. If the core is configured to boot from an address mapped to SDRAM, then U-Boot could have been copied to SDRAM by the host. Once U-Boot boots, it could then use FTP etc to boot the kernel blah blah ...
Yeah yeah, its contrived ...
Of course if the host is configuring all the registers, then there is probably no reason for the bootloader ... just boot to Linux directly from SDRAM.
Dave