On Tue, 8 Jan 2002, Alicia da Conceicao wrote:

: > You seem to have missed eCOS and RTEMS in there, both of which are
: > free for commercial use and offer friendly licensing terms.  Given
: > the lack of memory protection in uClinux, the only advantage it
: > offers over eCOS or RTEMS is the familiar programming environment,
: > at the cost of significantly more memory and processor overhead
: > and a license model that is not friendly to commercial products.
:
: I am not familar with RTEMS, but eCOS is the uClinux port by Redhat,
: and has the same lack of memory protection that uClinux has.

Systems lacking a MMU *imply* no memory protection.  A MMU is required for
memory protection.

: I am only considering a NetBSD non-MMU port at
: this stage, since I love NetBSD so much, even though I can
: continue to use uClinux for my embedded work.  I just thought I
: would ask the NetBSD guru's some advice before getting serious,
: since it would be a *HUGE* undertaking!

Yes.  Among the tasks that need to be done to make this happen:

* rip out UVM and UBC entirely via #if conditionals, and replace with buffer
  cache only

* rework toolchain to produce PIC code for all userland, including linked
  binaries

I'd estimate that the above alone would take at least several months.

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