Messages in this thread | | | From | Daniel Phillips <> | Subject | Re: Bug: Discontigmem virt_to_page() [Alpha,ARM,Mips64?] | Date | Thu, 2 May 2002 21:08:18 +0200 |
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On Thursday 02 May 2002 20:57, Andrea Arcangeli wrote: > On Thu, May 02, 2002 at 12:31:52PM -0700, Martin J. Bligh wrote: > > between physical to virtual memory to a non 1-1 mapping. > > correct. The direct mapping is nothing magic, it's like a big static > kmap area. Everybody is required to use > virt_to_page/page_address/pci_map_single/... to switch between virtual > address and mem_map anyways (thanks to the discontigous mem_map), so you > can use this property by making discontigous the virtual space as well, > not only the mem_map. discontigmem basically just allows that.
And what if you don't have enough virtual space to fit all the memory you need, plus the holes? Config_nonlinear handles that, config_discontig doesn't.
> > No, you don't need to call changing that mapping "CONFIG_NONLINEAR", > > but that's basically what the bulk of Dan's patch does, so I think we should > > steal it with impunity ;-) > > The difference is that if you use discontigmem you don't clobber the > common code in any way,
First that's wrong. Look at _alloc_pages and tell me that config_discontig doesn't impact the common code (in fact, it adds two extra subroutine calls, including two loops, to every alloc_pages call).
Secondly, config_nonlinear does not clobber the common code. If it does, please show me where.
When config_nonlinear is not enabled, suitable stubs are provided to make it transparent.
> Actually the same mmu technique can be used to coalesce in virtual > memory the discontigous chunks of iSeries, then you left the lookup in > the tree to resolve from mem_map to the right virtual address and from > the right virtual address back to mem_map. (and you left DISCONTIGMEM > disabled) I think it should be possible.
So you're proposing a new patch? Have you chosen a name for it? How about 'config_nonlinear'? ;-)
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