Porting Linux

Porting an Operating System means making it runnable on hardware which from begin shouldn't be supported by that OS.

For example, Linux was originally written for 386-class PCs (that was the first "port"). Later it was "ported" to the m68k architekture, which meant that it changed that way, that a motorola cpu (with a completely different instruction set) could run Linux.

uCLinux is a port of Linux onto architectures which don't have a MMU. Linux fundamentally requires a MMU to run and to work with the memory, but many (embedded) systems don't get one. So the linux kernel was changed. This "new" kernel doesn't require a MMU, but that meant also, that memory protection doesn't exist or isn't that strict to use. This may even have some other downsides, but -it runs-. And that's the point everything depends on.

Linux is changed so that this board is supported. That means e.g. a different set of hardware (no intel timer chip, no BIOS but firmware, different boot loading schemes, whatever) has to be supported. Another boot loader might be needed, so that the firmware is able to find, load and execute the kernel. This is meant by porting something.

Hope that helps, if not, ask further :-)

Regards

Hello Sebastin

That was a neat explanation of what my doubt was.. thanks for that.

regards

Krish. > > I have a real fundamental question.. Hoping someone point me to some

System means making it runnable on hardware which from

this board is supported. That means e.g. a

One thing to remember when writing operating systems as well as any other low level code is to watch up for the processor endiannes. For instance the x86 is little endian, while m68k is big endian. If the code is written in only one endiannes in mind, porting it to the other endiannes may require thousands and thousands of manual changes. However, if the code has been originally written so that it can run on both as big or little endian, this part of the porting job would be minimal.

Paul