bug in head.S

Paul Mackerras paulus at cs.anu.edu.au
Wed Jun 23 10:45:22 EST 1999

Nathan Sheeley <nsheeley at ibmoto.com> wrote:

> I was poking around in arch/ppc/kernel/head.S and I noticed this:
>   oris  r18,r8,0x20000000 at h
>   oris  r21,r11,(KERNELBASE+0x20000000)@h
>   mtspr DBAT2L,r18    /* N.B. 6xx (not 601) have valid */
>   mtspr DBAT2U,r21    /* bit in upper BAT register */
>   mtspr IBAT2L,r28
>                ^^^^^^^^^^^^^^^^Wouldn't r18 make more sense here?

Yep, sure, thanks for pointing that out.

> Has anyone tried to build/run a pmac SMP kernel with a recent (2.2.9)
> version of Linux?  

I have 2.2.10 running on my 2-cpu powermac at home (it's a 7500 with a
2 x 604e 200MHz cpu card in it).  It mostly runs fine but has frozen
up on me a couple of times - I haven't tracked down why/where yet.

> Can I expect a SMP kernel to boot on a UP?  I thought so, although it might

I would have thought so, as long as it's not a 601.  The SMP kernel
uses the tlbsync instruction which isn't implemented on the 601.


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