Re: [discuss] [Patch] 4/5 in support of hot-add memory x86_64 fix kernel mapping code

[keith mannthey <kmannth@us.ibm.com>]

On Sat, 2006-07-29 at 18:32 +0200, Andi Kleen wrote:
> On Saturday 29 July 2006 04:52, keith mannthey wrote:
> > Hello All,
> >
> >   phys_pud_init is broken when using it at runtime with some offsets.
> > It currently only maps one pud entry worth of pages while trampling any
> > mappings that may have existed on the pmd_page :(
> 
> To print x86-64 ptes you need a %016lx (or just %lx) 

Thanks. 
> it would be cleaner to recompute pmd inside the loop based on i
> and use a standard for() 

sure I can do away with the pmd++ pud++ in the for loops. 
> 
> It is unclear why you hardcode 0 as address in phys_pmd_update
> when a real address is passed in

When the pud is already set there a 2 options.  

1. You need to initialize pmds at the start of the pmd_page. 
2. You need to initialize pmds starting at some offset of the pmd_page.

When calling phys_pmd_init you need to pass it the start of the pmd_page
not some random pmd with in the page.  
pmd = alloc_low_page(&map, &pmd_phys); 
always gives us the start of the pmd_page.  I keep this idea for the
update path as well. 
pmd_offset(pud,0) does just this. Maybe there is a better macro to use?

Things could be different is terms of flexibility of what you pass in
(more changes are involved) but this set of changes seemed to be min-
tampering of the current code. 

Also in general is there some reason kernel mapping code is arch
specific?  This all seems to be pretty generic.

Thanks,
  Keith