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http://mailman.uclinux.org/pipermail/uclinux-dev/2003-September/020871.html Phil Wilshire philwil at earthlink.net Fri Sep 5 08:32:02 EDT 2003
HI Thomas, If you have a system with an MMU you get demand paging copy on write etc. Also memory fragmentation can be less of a problem. On the Arm MMU the whole system is devided up into either 1M blocks or 4K blocks. A contiguous block of vitrual memory can be made up of a number of 4K pages scattered anywhere in Physical Memory. You also get e true fork that may make some applications work better. You may loose some of the ability to touch hardware directly from user space but you can arrange for this hardware to still be mapped accordingly. One big gain, on the ARM platform is that you can use shared libraries. Brining up odd memory layouts and new hardware with an MMU can be tricky. regards Phil Thomas Chen wrote: > > i am wondering whether processors both with CACHE and running > about same clock, one with MMU, one without MMU, which one > would perform better? > > more specifcally, we are talking about CX82100 (ARM940T) and > i am about to get a AT91RM92 (ARM920) both about same clock > speed, but one has MMU (920), would one perform better than > another ??? > > on 9/4/03 8:06 PM, Greg Ungerer at gerg at snapgear.com wrote: > > > Hi Thomas, > > > > thomas chen wrote: > >> any idea on the speed of this processor (thats a lot of device... probably > >> need > >> some horsepower!) > > > > From the Conexant CX82100 brochure: > > > > . 168MHz > > . ARM 940T core > > . 2 10/100 ethernet MACs with integrated MII > > . USB 1.1 interface > > > > > > Regards > > Greg > > > > > > > > > >> Greg Boehnlein wrote: > >> > >>> Hello, > >>> Apparently, my message about hacking the Actiontec Dual PC Modem > >>> has stirred up quite a bit of activity. There is now a group of people > >>> trying to determine what the hardware platform is, if/how we can rebuild a > >>> uClinux kernel for it and what might be possible with the boxes. At $50 > >>> for an embedded platform with 2 Megs of Flash and 8 megs of ram with Dual > >>> Ethernet ports and a built in Modem, there are plenty of interesting > >>> oprtions! > >>> > >>> Linux version 2.4.6 (smao at localhost.localdomain) (gcc version 2.95.3 > >>> 20010315 (release)) #14 Sat Aug 16 21:02:40 PDT 2003 > >>> > >>> We have determined that the board is running a Connexant > >>> processor CX82100-41 processor. Pictures of the board can be seen at: > >>> http://damin.umlcoop.net/~delink > >>> > >>> This processor appears to be running an ARM 940 CPU. Does anyone > >>> have any idea where/how/if there is a publically available toolchain that > >>> we can use to accelerate our efforts? Obviously, Actiontec has one, but we > >>> don't have access to their tools (yet.. we are working that issue with > >>> them). At the very least, the kernel source code and any modifications > >>> they have made to get it to run on the platform should be released to the > >>> public under the GPL, but we would really like to see if the uClinux > >>> community has already done the heavy lifting. |
