On Sun, Apr 08, 2001 at 06:42:41PM -0400, John Tobey wrote:
> The CPU is a QED RM5231 (CONFIG_NEVADA) 150MHz. May I assume that
> nobody has run a 64-bit kernel on this thing? The RaQ has no video
> card but a serial console, PCI, IDE, Ethernet, and special LEDs, panel
> buttons, and LCD display. If I can get a 64-bit kernel to boot and
> prove its existence through any of these devices, I will be drunk with
So far the only supported machine by the mips64 kernel is the SGI Origin
200 / 2000 series.
> The reason I want 64 bits is that I (a) want a challenge, (b) plan to
> write an application that uses a sparse address space (40 bits is
> better than 31), (c) plan to outlive the 31-bit time_t, and (d) am
> p.o.ed at having bought the thing based on misleading advertising that
> mentioned a 64-bit processor but not the 32-bit OS.
> Big/little endian macht nichts. I guess big will be easier, and I'm
> not concerned with running any existing 32-bit binaries.
Go for little endian because the firmware is little endian; supporting
``other-endian'' for userspace would be unecessary extra pain. We already
have suport for 32-bit binaries in the 64-bit kernel; in fact ALL
software we run on 64-bit kernels is 32-bit.
32-bit wasn't only the easy thing to do - it's also the more efficient
thing for most software which doesn't need 64-bit registers or 64-bit
address space. For a system with a dog slow 32-bit memory bus such as
the Qube 64-bit kernels would mean a dramatic slowdown.
I admit it's interesting though, mostly for engineering reasons, not
as a platform.
> I imagine that I would start by grafting Cobalt's peripheral support
> code from arch/mips/cobalt (now defunct) and include/asm-mips/cobalt.h
> into the mips64 tree from email@example.com:/cvs/linux.
Somebody else was already working on upgrading the Cobalt kernel to 2.4.