Re: How can I detect a SMP box with d-i kernel and tools ?

[Sven Luther <sven.luther@wanadoo.fr>]

On Fri, Aug 13, 2004 at 08:33:48AM +0200, Sven Luther wrote:
> On Fri, Aug 13, 2004 at 12:13:20AM +0200, Thomas Poindessous wrote:
> > Hi,
> > 
> > I'm trying to add smp detection for Bug#265098
> > 
> > I'm looking for a way to detect smp system with current d-i powerpc
> > kernel and d-i tools.
> > 
> > If you know such a trick, I will be glad to know it.
> 
> I think the easiest way would be to look in the /proc/device-tree, for the
> info given to you by the OF. This naturally will probably only work on
> newworld and chrp, not sure about oldworld and prep SMP boxes.
> 
> Anyway, on my pegasos2/G4, i have :
> 
>   $ ls /proc/device-tree/cpus/
>   #address-cells  #cpus  linux,phandle  name  PowerPC,74x7  #size-cells
> 
> Presumably you have two processor nodes on SMP boxes.
> 
> Also, another way would (maybe) to look at the content of #cpus :
> 
> $ hexdump /proc/device-tree/cpus/#cpus
> 0000000 0000 0001
> 0000004
> 
> So, on my box, #cpus will contain 1, and presumably on SMP boxes, it will
> contain 2 or more. I have not tested this, but please check on your system.

I hear that :

  1) older models may have /proc/device-tree/cpu only.

  2) /proc/device-tree/cpus/#cpus does not exist on G5 boxes.

  3) best would be to count the directories in /proc/device-tree/cpu or
  /proc/device-tree/cpus. early G5 and maybe some other boxes may have a bug
  though which make the second cpu node appear in the cpu node.

Here is a smallish irc excerpt about this issue : 

08:49 < benh> benh@pogo:/proc/device-tree$ ls -l cpus/
08:49 < benh> total 4
08:49 < benh> -r--r--r--    1 root     root            4 Aug 13 16:42 #address-cells
08:49 < benh> -r--r--r--    1 root     root            4 Aug 13 16:42 #size-cells
08:49 < benh> dr-xr-xr-x    3 root     root            0 Aug 13 16:42 PowerPC,970
08:49 < benh> dr-xr-xr-x    3 root     root            0 Aug 13 16:42 PowerPC,970
08:49 < benh> -r--r--r--    1 root     root            4 Aug 13 16:42 linux,phandle
08:49 < benh> -r--r--r--    1 root     root            5 Aug 13 16:42 name

08:54 < owen-pb> [owen@build cpus]$  find . -type d
08:54 < owen-pb> .
08:54 < owen-pb> ./PowerPC,970
08:54 < owen-pb> ./PowerPC,970/PowerPC,970
08:54 < owen-pb> ./PowerPC,970
08:54 < owen-pb> ./PowerPC,970/PowerPC,970
08:51 < svenl> owen-pb: you have a SMP box ?
08:51 < owen-pb> svenl: yup

$ find . -type d
.
./PowerPC,74x7
./PowerPC,74x7/l2-cache
./PowerPC,74x7/l3-cache

Hope this helps.

Friendly,

Sven Luther