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From: Andi Kleen <ak@suse.de>
To: Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [RFC PATCH 01/09] robust VM per_cpu core
Date: Wed, 17 May 2006 13:08:54 +0200
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On Wednesday 17 May 2006 12:46, Steven Rostedt wrote:
> 
> On Wed, 17 May 2006, Andi Kleen wrote:
> 
> >
> > > As well as the following three functions:
> > >
> > > pud_t *pud_boot_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long addr,
> > >                      int cpu);
> > > pmd_t *pmd_boot_alloc(struct mm_struct *mm, pud_t *pud, unsigned long addr,
> > >                      int cpu);
> > > pte_t *pte_boot_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long addr,
> > >                      int cpu);
> >
> > I'm not sure you can just put them like this into generic code. Some
> > architectures are doing strange things with them.
> 
> Hmm, like what?

Mostly managing their software TLBs I think.
 
> >
> > And we already have boot_ioremap on some architectures. Why is that not
> > enough?
> 
> I thought about using boot_ioremap, but it seems to be an abuse.  Since
> I'm not mapping io, but actual memory pages. 

We already use it for memory, e.g. for mapping some BIOS tables.

> So the solution to that 
> seemed more of a hack.  I then would need to worry about grabbing pages
> that were node specific 

alloc_bootmem_node

> and getting the physical addresses.  

virt_to_phys() 

[ + hacks to handle 32bit NUMA unfortunately ]

-Andi