Re: SMP/UP kernel S01E02

[Bill Hacker <wbh@xxxxxxxxxxxxx>]

Thomas E. Spanjaard wrote:
> Dmitri Nikulin wrote:
> > On 3/24/07, Gergo Szakal <bastyaelvtars@gmail.com> wrote:
> > > Well, I've been thinking of the SMP/UP issue many times, and the best 
> > > solution would be if SMP kernels could boot on UP machines. I have 
> > > plenty UP boxes and a few SMP boxes to test on. I am not claiming 
> > > anyhing, this is just 'food for thought'.
> > Don't they? I thought the only problem for most cases is that the SMP
> > kernels do more heavyweight locking and are therefore slower, and
> > without the gain of parallelism on UP it's a pure loss.
>
> DragonFly SMP expects multiple processors, and will die if it doesn't 
> find any, iirc when it tries to detect other APICs. As an example of 
> working SMP-kernel-on-UP-hardware, see NetBSD (which doesn't involve 
> boottime binary patching, btw).
>
> Cheers,

Haven't looked into *how* FreeBSD 7-CURRENT i386 (not - 64 or AMD -64) does it, 
but it does it, as did 6.2-PRE AMD-64. (Tyan MB, two different Celeron, one 
single, one dual-core).

7-CURRENT boots unaltered on MSI-PM8M2V with Celeron single-core and Asus 
P5VDC-MX with P4 Core-D dual-core.

All Socket 775 gear.

/var/run/dmesg.boot tells the tale, and 'top' adds the column for which CPU is 
in use automagically.

Dragonfly 1.8, installed with the UNI MB,  is not (so far) willing to boot on 
the SMP MB. Will try a re-install later.

Unless there is a switch I can edit from the live-CD...  ??


Bill