Date: Fri, 25 Jul 2008 00:39:00 +0300 From: Oleksandr Tymoshenko <gonzo@freebsd.org> To: Jerry Toung <jrytoung@gmail.com> Cc: freebsd-mips@freebsd.org Subject: Re: mips_phys_mask define Message-ID: <4888F674.4010004@freebsd.org> In-Reply-To: <86068e730807241333v4d9f35d4ve4e4a266bb6d8121@mail.gmail.com> References: <86068e730807241333v4d9f35d4ve4e4a266bb6d8121@mail.gmail.com>
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Jerry Toung wrote:
> Hello list,
> still learning. Could someone explain why
> MIPS_PHYS_MASK is 0x1fffffff and not 0x7fffffff when you want to convert a
> program's address
> back to physical?
MIPS_PHYS_MASK is used to convert addresses from KSEG0 and KSEG1 to physical
ones. KSEG0 and KSEG1 are 2**29 bytes each. So the mask should be 2**29 - 1.
That gives us 0x1fffffff.
I'd suggest you to read MIPS32(tm) Architecture For Programmers Volume III:
The MIPS32(tm) Privileged Resource Architecture. It's a nice starting point.
You can download the document from mips.com site.
--
gonzo
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