Re: [PATCH] HPET driver

From: Jeff Garzik
Date: Thu May 13 2004 - 18:50:48 EST

Andrew Morton wrote:
Jeff Garzik <jgarzik@xxxxxxxxx> wrote:

+ vma->vm_flags |= (VM_IO | VM_SHM | VM_LOCKED);
+ vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+ addr = __pa(addr);

where did these flags come from? don't you just want VM_RESERVED?

VM_IO is the way to mark mmapped I/O devices.

vma->vm_flags |= VM_IO;

should be sufficient here.

hm, I'm trying to decrypt how the driver accesses the hardware. It's
taking copies of kernel virtual addresses based off hpet_virt_address, but
there are no readl's or writel's in there. Is the actual device access
done over in time_hpet.c?

HPET writes into RAM at magic addresses, so it's not really a bus address.

Thus I think only VM_RESERVED is needed...


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at