From: jan@swi.psy.uva.nl (Jan Wielemaker) Subject: Re: NT vs Linux (was: Re: truth or dare) Date: Fri, 9 Jul 1993 08:09:28 GMT
imp@boulder.parcplace.com (Warner Losh) writes:
>In article <MUTS.93Jul7072935@muts.hacktic.nl> muts@muts.hacktic.nl
>(Peter Mutsaers) writes:
>>Name me another thing common to all modern unices
>>and missing on Linux.
>A generic mmap(2).
Funny. I'm using mmap() for realising dynamically expanding memory for
SWI-Prolog (mapping /dev/zero, MAP_PRIVATE). This feature was designed
o SunOs. It's nice: no software testing for stack overflow and no shifting
the stacks!
I was naive and told it would mork on may modern unices. Tried many ...
Sofar only Linux (from 99pl7) passed the test. For the others: on some,
if you map twice you will see the same page of physical memory appearing
at two places (this is called stack sharing I guess :-) On others you
can't map at arbitrary addresses (I *know* is limited to multiples of
the page size, but why on some machines to multiples of 0x20000000 or
so???)
P.s. I know the functionality of Linux' mmap() is limited. I'm only
stressing that the part that *is* available is robust and appears to
be designed to help the programmer writing programs that work.
To summarise, I'm very happy with Linux. All my 3 MB C-code with a
lot of close-to-os stuff written on SunOs ran in two days. Most of the
problems where just bugs in my code which happen to pass in SunOs.
Linux only crashed once ... after replacing /etc/init without rebooting
immediately!
--- Jan