[ALTERA] NIOS-II + MMU + FPU

FYI: Linux is not unix. Also, linux does not require an MMU.

--buddy

Is uclinux the same as Linux? I thought the kernel and the executables were considerably different.

99% of the kernel code is identical. From 2.6 onwards, uClinux (ie nommu) support is integrated into Linus' root source tree. For 2.4 kernels, uClinux is a patch that *adds* to Linux, nothing is removed.

In the microblaze port for example, we take drivers written by MontaVista for the PPC/V2Pro kernel, and drop them in directly. Some small modifcations are required usually due to differences in kernel configuration mechanisms, not fundamental architectural issues.

From an application programming perspective, much of the time apps are source compatible between linux and uClinux. I recently took some ntp (network time protocol) tools and had then running on my microblaze uClinux board in under half an hour. No source code changes required.

nommu means no fork(), you use vfork instead. Many Linux/Unix programs use the sequence fork()/exec() - this is easily ported to vfork. Other, more complex uses can be a bit trickier. pthreads works on uClinux platforms.

uClinux uses a different executable file format (called flat binaries), rather than ELF. However, the build environment and tools automatically handles the creation of these files. Once your board has booted, they are just executables, same as any other.

Read the following excellent article by Dave McCullough if you'd like to learn more about the differences (and lack thereof):

Regards,

John

Followup to: By author: Buddy Smith In newsgroup: comp.arch.embedded

However, if you take "Unix-like" as an adjectival phrase, and the parenthesis as definitional (therefore avoiding arguments about its validity), it makes sense:

"This would make it possible to run the standard Unix-like Linux, i.e. the one which requires an MMU."

Desipire ucLinux, there is clearly still a win in having an MMU for running Linux.

-hpa

Hi Markus,

I cannot comment on specifics of future releases, but please watch for official press releases concerning Nios II - they will let everyone know about new features - stay tuned :)

Jesse Kempa Altera Corp.