Subject: TLB manager for devices -- Re: CVS commit: src
To: None <port-pmax@NetBSD.org, port-mips@NetBSD.org>
From: Toru Nishimura <firstname.lastname@example.org>
Date: 04/26/1999 15:57:54
>> To support the i860 properly, we need a TLB manager and the
>> right ucode for the damn thing.
> Special TLB management framework will be required ultimately to
> support the variety of devices found in Alpha/DECstations (think about
> R4000 and Alpha TLB)
NetBSD/mips common code leaves 6 entry of R3000 hard-wired TLBs for no
purpose. These can over upto 24KB of memory region. Are they useful
with your driver?
R4000 descenders can program TLB entries to cover different size of
address space like other modern procesors can do. This feature is
originally designed to map framebuffer without sacrifing TLB runtime
dynamism. It'd be nicer to have flexible TLB manager interface for
devices, I think. As a side note, some of R4000 TLB entries are wasted
too with current NetBSD/mips mainly due to lack of such the manager.
(But, it's ok to call "mtc0 ..." directly even with current code base.)
Nara Institute of Science and Technology