Subject: Re: Striped down NetBSD kernel for 802.11b AP units?
To: None <email@example.com>
From: Thor Lancelot Simon <firstname.lastname@example.org>
Date: 01/18/2002 12:00:13
On Fri, Jan 18, 2002 at 11:31:19AM -0500, Nathan J. Williams wrote:
> > Are any of our arch's similar to the AMD ELAN SC400 mentioned above?
> The AMD Elan product line are embedded x86-compatible devices. The
> SC400, for example, is a 486 clone core with on-chip memory
> controller, PC-style system logic (PIC, timers, etc), serial port,
> parallel port, keyboard port, and a dual-slot PCMCIA controller.
> It would probably be pretty easy to get NetBSD/i386 to run on such a
> system; the difficult part would be putting the system image somewhere
NetBSD already runs on such systems; I have several of them. No changes
to NetBSD were required.
On the other hand, such systems pretty much totally suck, because although
AMD put a 133MHz SDRAM interface on the SC400, and the CPU core runs at
133MHz, they left a 32-bit, 33MHz pipe between them -- so the result is
a chip that runs far more slowly than even a 133MHz single-issue x86 should.
From long experience with macro- and micro- optimizations on this exact
platform, I can tell you that you will have quite a bit of trouble getting
more than about 50Mbit/sec through the box. An Ethernet controller with
hardware checksum support might help some, since memory bandwidth is the
primary constraint on the machine's performance, but if you pay for two
of those, you might as well have bought a better CPU.
Note that the Elan has no VGA; if you want an X terminal, you want something
like a Cyrix MediaGX instead.