Date: Thu, 05 Sep 1996 10:00:25 -0400 From: Gary Chrysler <tcg@ime.net> To: shadows@kuwait.net Cc: freebsd-questions@FreeBSD.org Subject: Re: 2.1.5-RELEASE installation question Message-ID: <322EDCF9.2345@ime.net> References: <Pine.NEB.3.94.960905081634.16588C-100000@broken.whitefang.com>
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The ShadowS Know wrote:
>
> On Wed, 4 Sep 1996, Gary Chrysler wrote:
>
> > Paul T. Root wrote:
>
> > > For EIDE drives, the root partition *MUST* be completely contained within
> > > the first 504Meg of the drive, due to the PC architectures BIOS limitations.
> > >
> >
> > That applies to all IDE bootable devices, Not just EIDE.
>
> Well I installed 2.1.5 on an EIDE and even though it does start in the
> first 504 megs its not *completely* contained in it. Is this causing some
> problem I'm not aware of? I've only experienced it bieng slow, and I
> figured its like that since there is no EIDE driver (or so the kernel
> LINT config file said).
>
The importance is that the bootable partition be fully inside
the first 1024 cylinders (~504M), The rest dosn't matter.
In FreeBSD's case this is the / slice! (root slice)
The Limit:
Is in the Systems BIOS INT 13 functions 16 bit registers.
DX - 8 bits for head number.
8 bits for drive number.
CX - 10 bits for cylinder number.
6 bits for sector number.
The largest 10 bit number possible is 1023, Thus the limit on
numbers of cylinders is 1024. (0-1023)
What fries me is, DX allows 255 drives.
-Enjoy
Gary
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