From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,55b1f15723dd43ba X-Google-Attributes: gid103376,public From: dennison@telepath.com Subject: Re: Compiler Hosts and Targets Date: 1998/12/18 Message-ID: <75dr0b$h$1@nnrp1.dejanews.com>#1/1 X-Deja-AN: 423609089 References: <755s4v$7vh$1@nnrp1.dejanews.com> <75c6ir$l61$1@nnrp1.dejanews.com> X-Http-Proxy: 1.0 x14.dejanews.com:80 (Squid/1.1.22) for client 204.48.27.130 Organization: Deja News - The Leader in Internet Discussion X-Article-Creation-Date: Fri Dec 18 15:05:49 1998 GMT Newsgroups: comp.lang.ada X-Http-User-Agent: Mozilla/4.5 [en] (WinNT; I) Date: 1998-12-18T00:00:00+00:00 List-Id: In article <75c6ir$l61$1@nnrp1.dejanews.com>, dewarr@my-dejanews.com wrote: > In article <755s4v$7vh$1@nnrp1.dejanews.com>, > dennison@telepath.com wrote: > > Non-Ada issue: There is no such thing as Pentium/VxWorks, > > unfortunately. > > There is an Intel3(or4)86/VxWorks target, which may be > > used on Pentiums > > (although it will run *slower* unless you change the > > caching behavior!). But > > if you use that on a Pentium it will not generated > > Pentium optimized code. > > Not quite clear what "it" refers to here. VxWorks is not > in the business of "generating" code at all! It is of > course the case that compilers typically used with VxWorks, > including gcc, and GNAT, can of course generate Pentium > optimized code. Of course "it" was a simplification. I didn't think anyone here was interested in the gory details. But since you seem to insist upon them I'll go ahead. The rest of you may want to go get a sandwich or something. :-) Tornado, the system that came w/ our VxWorks (targetted to a PC clone) contained the source code for the OS, a BSP for the PC, gcc, and a GUI environment for building the OS and user programs. The BSP's that are available are for PC386 and PC486 (no "PCPentium", no "PCPentiumII"). The gcc we get is a prebuilt version for the 386 (not "Pentium", 386). With this system as shipped, you cannot build Pentium targetted code. (I suppose its possible they have a bare Pentium BSP, but that wouldn't be much fun to use on a PC unless you enjoy writing device drivers). The compiler we use is the GreenHills Ada compiler, which to my knowledge is the *only* validated Ada compiler on this platform. (Rational does have some VxWorks compilers for other CPU's). The GreenHills compiler cannot build PentiumII or Pentuim optimized code; only 368 and 486. The bug I was referrring to is a known VxWorks bug in this configuration. The OS performs a cache invalidate whenever a task switch occurs. Apparently this instruction takes roughly 5 cycles on the Pentium, but 2000 on the Pentium II. If you run your system with relatively high rate tasks (2KHz in our case), this causes a Pentium II system to run *slower* than Pentium I. We have measured this in house (and we are not the only ones). The folks at WindRiver actually sent someone out here to track it down, and ended up changing our OS source files to get around the problem (*much* better now). Everyone back from the fridge yet? Good. The point is that while you can run a VxWorks system on a Pentium PC, neither VxWorks, not Tornado, nor Green Hills are really designed for it. -- T.E.D. -----------== Posted via Deja News, The Discussion Network ==---------- http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own