Re: [patch 4/6] xip: support non-struct page backed memory

["Jared Hulbert" <jaredeh@gmail.com>]

>  (The kaddr->pfn conversion may not be quite right for all architectures or XIP
>  memory mappings, and the cacheflushing may need to be added for some archs).
>
>  This scheme has been tested and works for Jared's work-in-progress filesystem,

Opps.  I screwed up testing this.  It doesn't work with MTD devices and ARM....

The problem is that virt_to_phys() gives bogus answer for a
mtd->point()'ed address.  It's a ioremap()'ed address which doesn't
work with the ARM virt_to_phys().  I can get a physical address from
mtd->point() with a patch I dropped a little while back.

So I was thinking how about instead of:

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
void * get_xip_address(struct address_space *mapping, pgoff_t pgoff,
int create);

xip_mem = mapping->a_ops->get_xip_address(mapping, vmf->pgoff, 0);
pfn = virt_to_phys((void *)xip_mem) >> PAGE_SHIFT;
err = vm_insert_mixed(vma, (unsigned long)vmf->virtual_address, pfn);
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

Could we do?

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
int get_xip_address(struct address_space *mapping, pgoff_t pgoff, int
create, unsigned long *address);

if(mapping->a_ops->get_xip_address(mapping, vmf->pgoff, 0, &xip_mem)){
     /* virtual address */
     pfn = virt_to_phys((void *)xip_mem) >> PAGE_SHIFT;
} else {
     /* physical address */
     pfn = xip_mem >> PAGE_SHIFT;
}
err = vm_insert_mixed(vma, (unsigned long)vmf->virtual_address, pfn);
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

Or maybe like...

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
unsigned long get_xip_address(struct address_space *mapping, pgoff_t
pgoff, int create, int *switch);

xip_mem = mapping->a_ops->get_xip_address(mapping, vmf->pgoff, 0, &switch);
if(switch){
     /* virtual address */
     pfn = virt_to_phys((void *)xip_mem) >> PAGE_SHIFT;
} else {
     /* physical address */
     pfn = xip_mem >> PAGE_SHIFT;
}
err = vm_insert_mixed(vma, (unsigned long)vmf->virtual_address, pfn);
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

Or...

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
void get_xip_address(struct address_space *mapping, pgoff_t pgoff, int
create, unsigned long *phys, void **virt);

mapping->a_ops->get_xip_address(mapping, vmf->pgoff, 0, &phys, &virt);
if(phys){
     /* physical address */
     pfn = phys >> PAGE_SHIFT;
} else {
     /* physical address */
     pfn = virt_to_phys(virt) >> PAGE_SHIFT;
}
err = vm_insert_mixed(vma, (unsigned long)vmf->virtual_address, pfn);
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

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