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Re: [Milkymist port] virtual memory management
On Feb 18, 2014, at 3:54 AM, Yann Sionneau <yann.sionneau%gmail.com@localhost>
> Le 10/02/14 23:00, Yann Sionneau a écrit :
>> Thanks for all your explanations, if everything I said here is correct
>> (which would mean I understood correctly your answer) then I think I'm ready
>> to implement all this :)
> I have made good progress on the NetBSD port, it is now booting up to
> enabling interrupts and cpu_initclocks() call, see the boot log .
> But then I am wondering how I can map the memory mapped registers of the
> timer0 of Milkymist SoC in order to use it as the main ticking clock.
> Basically, I need to map physical address 0xe000.1000 somewhere in kernel
> virtual memory.
> Is there somewhere a function like vaddr_t map_paddr(paddr_t, prot)?
> I could indeed walk the kernel page table and insert somewhere in a free PTE
> (a NULL one) a reference to the 0xe000.1000 physical address, but then how to
> be sure that the vm subsystem will not allocate this virtual address twice?
> Is there an "iomapping" mechanism?
> Thank you for your help :)
>  -- http://pastebin.com/MYitt9L4
see bus_space(9), specifically bus_space_map.
internally, it allocates some KVA via uvm and uses pmap_kenter_pa to
map the I/O address via the allocated KVA.
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