[syslinux] Hyperthreaded P4 processor count

[Rip Toren]

Terry Barnaby wrote:

> I have what may be a similar problem with syslinux. As noted previously
> in the list if I use apm=power-off on the kernel boot line with syslinux
> on an SMP system I get a kernel error message from the apm system.
> It seems that there is some issue with syslinux and multiple processors.
> This happens on two systems. Lilo and grub are fine.....
>
> In my case Linux comes up and recognises all of the processors though.
>
> Terry
> Petro wrote:
>
>> On Thu, Jan 22, 2004 at 02:32:16PM -0500, Rip Toren wrote:
>>  
>>
>>> I have three different live-CD distributions that give me different
>>> numbers for the cpu count on this box (Dell P4 2.4GHz).
>>> -the Knoppix 3.3 (11-19-03) says 1 processor (no error);
>>> -the PHLAK 0.2 distribution say 1 processor (and 1 missing)
>>> -the Local Area Security distro says two processors (identicle P4s).
>>> Might there be somthing new in 2.0.8 that accounts for this 
>>> difference. Is there a switch or whatever that kicks the senond one 
>>> into play?I would love to add the 2nd processor (given the kernel is 
>>> SMPed).
>>>   
>>
>>
>>    There isn't really anything that syslinux does where a second
>>    processor would help.
>>    It's the linux (or whatever kernel) you boot later that kicks it in.
>>   
>

Just posting research results....
 I think this is done in vmlinuz at the initial boot loader.
 
 During the boot, it starts with
 1) Syslinux banner line flashes on top of screen momentarily
 2) Boot graphic and prompt (from inside boot.img) are presented
 3) options selected, or not, then <cr>
 4) vmlinuz.........
 5) miniroot.gz.........
 6) screen clears
 7) 1 or more Tuxs apear at top of screen (appers to == processor count)
 8) Some welcome string:
       knoppix = Welcome to (multicolored) KNOPPIX Live-CD
       L.A.S = Now booting Local Area Security 0.4.1
 9) Found xxxx memory
 
 At Step #8 we are at the first (almost) executable line of the 
'linuxrc" script. This script is the only executable thing in the 
miniroot.gz, inside the boot.img.
 
 The next action for linuxrc is to 'mount /dev/proc /proc". This is 
where the commandline and cpuinfo information are taken from. The number 
of processors is already known prior to lynixrc, the compressed file 
system with the kernel are not yet looped and mounted yet.
 
 The tailend of vmlinuz must be what loaded that '/dev/proc' structure 
just before clearing the screen and putting up the Tux and starting the 
linuxrc after opening miniroot.gz.
 
 Also, the knoppix kernel is labeled as 2.4.22-xfs, and the L.A.S kernel 
is 2.4.20-xfs. The options configuration for Knoppix does set the only 
occurance of "xxx-SMP = y".
 
 BillS