From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <393D3D63.E3504DE9@embeddededge.com> Date: Tue, 06 Jun 2000 14:05:23 -0400 From: Dan Malek MIME-Version: 1.0 To: Tom Montgomery CC: "linuxppc-embedded@lists.linuxppc.org" Subject: Re: Running from ROM References: <200006052137.RAA29282@rome.wavemark.com> <393C23CC.3289DD1F@mvista.com> <00060516034300.24189@minotaur.mvista.com> <200006061339.JAA30741@rome.wavemark.com> <393D06BD.ADEDF247@miranda.com> Content-Type: text/plain; charset=us-ascii Sender: owner-linuxppc-embedded@lists.linuxppc.org List-Id: Tom Montgomery wrote: > .... What I have gathered from > lurking here is that embedded linux operates like PC linux, and that is > not the model we are looking for. Hmmm. It is quite different from a workstation version from my perspective. On the other hand, the workstation version of Linux contains many features we can (and want to) utilize. If you want to make Linux look like a primitive RTOS, you can hard code a bunch of variables and write some simple kernel threads and be done. Most people are tired of primitive RTOS environments and want something with the features and configurability of a workstation in a smaller package. That's probably why embedded Linux appears to look like a workstation to you. Why not utilize those features when it is beneficial? > .... Running from ROM makes sense to us, > too. OK, explain this to me. It doesn't make any sense to me for the following reasons: Flash ROM is more expensive than equivalent sized DRAM Flash ROM is more difficult to acquire I can compress the kernel and file system into a single 8-bit device, saving substantial board space. Flash ROM is typically slower access than DRAM Small DRAM parts are getting harder to find and more expensive, so you may as well use more DRAM Running the kernel from flash may save 600K or so of RAM and require an additional 500K of Flash ROM (because it isn't compressed any more) I have seen some very versatile and cost effective systems that use a tiny Flash rom and Compact Flash for storage. Above some size (like 16 Mbytes or so), Compact Flash is more economical than soldered on board flash. It is also much easier to manage and adds product flexibility. Execution from Flash ROM is harder to debug and configure, increasing development time. I like learning new things.....explain why running from Flash is better for your system. -- Dan ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/