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SubjectWould Linux still be Linux if it didn't have an MMU was Re: Linux Port to NS486? (without MMU)
On Mon, 14 Oct 1996, Steve VanDevender wrote:
> Unfortunately according to the web pages you cite the NS486SX doesn't
> have an MMU, which is absolutely required to run Linux:

http://www.national.com/ns486/super/slide7.html does state
> >A few features, such as an
> >MMU and floating point, were not implemented.
and I think this is confirmed in the NS486
Programmer's Guide & Reference Manual (3.95 MB PDF file)
http://www.national.com/appinfo/ns486/ns486sxf.pdf

Steve VanDevender said:
> Without an MMU your only hope is that the people who are doing
> Linux-8086 might support it.

I noticed that the Programmer's Guide & Reference Manual
also states a Key Feature of the NS486 is:
> 100% compatible with VxWorks, VRTX, QNX, pSOSa TM , and other popular
> real-time executives and operating system kernels.

When I read the man page for mmap it states that
"Linux 0.99.11 can't map files etc., and can't do
other things documented here" -- I probably have
old manpages. This leads me to think that early
linux didn't have much support for mmap.

Do these other OS's support mmap? If they can
work around it, would Linux workarounds still be Linux?

Many of the mmap calls that I've seen seem to be
mostly to malloc and read files.

If the kernel were to 'simulate' mmap for the simple
cases - to allow some applications to work, would
it still be "linux"?

I grep'ed for mmap in the posix test cases
and didn't find any test's for it, so I guess
that POSIX doesn't require mmap either.
ftp://tsx-11.mit.edu/pub/linux/sources/test_suites/NIST-PCTS.tar.gz




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