Hi all,
I'm trying to use virt_to_phys() to find the physical address
of some kernel RAM. (This is an on ARM OSK board).
It's not working as I expected:
membase = kmalloc(DEBUG_MEM_LENGTH, GFP_ATOMIC);
physbase = virt_to_phys(membase);
printk("membase=0x%p\n", membase);
printk("physbase=0x%lu\n", physbase);
Gives me:
membase=0xc1c8c000
physbase=0x298369024
physbase isn't in the range of real physical memory on my
machine. (I'm only interested in the first page of the
allocation, so I don't care if subsequent pages are
not physically contiguous.)
Other uses of virt_to_phys() that I see in the the kernel source
seem to only use IOmapped mem, or DMA-able mem.
Is this even the right approach? Do I need to walk page
tables myself? I thought there would be a simple routine
for this, but I haven't found it.
Any help would be much appreciated.
Thanks,
-- Tim
=============================
Tim Bird
Architecture Group Chair, CE Linux Forum
Senior Staff Engineer, Sony Electronics
=============================
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