Re: C/H/S from user space

[Jeff V. Merkey]

And a very useful translation table for coversion to 63 head models.

Jeff

// Use the Phoenix method of drive translation
// to translate drive geometry for those drives
// that exceed 1024 cylinders in size.
//
// Phoenix Geometry Translation Table
// -----------------------------------
//
// Phys Cylinders Phys Heads Trans Cyl Trans Heads Max
// --------------------------------------------------------
// 1 <C<= 1024 1 <H<= 16 C = C H = H 528 MB
// 1024 <C<= 2048 1 <H<= 16 C = C/2 H = H*2 1.0 GB
// 2048 <C<= 4096 1 <H<= 16 C = C/4 H = H*4 2.1 GB
// 4096 <C<= 8192 1 <H<= 16 C = C/8 H = H*8 4.2 GB
// 8192 <C<= 16384 1 <H<= 16 C = C/16 H = H*16 8.4 GB
// 16384 <C<= 32768 1 <H<= 8 C = C/32 H = H*32 8.4 GB
// 32768 <C<= 65536 1 <H<= 4 C = C/64 H = H*64 8.4 GB
//
// LBA Assisted Translation Table
// ------------------------------
//
// (NOTE: The method below is an alternate method for
// translating large drives that does not place any limits
// on reported drive geometry. It has the disadvantage
// of always assuming 63 Sectors Per Track.)
//
// Range Sectors Heads Cylinders
// -----------------------------------------------------
// 1 MB <X< 528 MB 63 16 X/(63 * 16 * 512)
// 528 MB <X< 1.0 GB 63 32 X/(63 * 32 * 512)
// 1.0 GB <X< 2.1 GB 63 64 X/(63 * 64 * 512)
// 2.1 GB <X< 4.2 GB 63 128 X/(63 * 128 * 512)
// 4.2 GB <X< 8.4 GB 63 255 X/(63 * 255 * 512)
//

// Adjust cylinder and head dimensions until this drive
// presents a geometry with a cylinder count


linux-os (Dick Johnson) wrote:

> On Fri, 17 Feb 2006, Phillip Susi wrote:
>
>  
>
> > linux-os (Dick Johnson) wrote:
> >    
> >
> > > Yes, it's a very good model, in fact what I've been talking about.
> > > However, several people who refused to read or understand, insisted
> > > upon obtaining the exact same C/H/S that the machine claimed to
> > > use when it was booted.
> > >
> > >      
> > That's because if you don't use the same geometry that the bios reports
> > when calculating the CHS addresses of the sectors you intend to load,
> > you won't be requesting the right sectors from int 13.
> >    
>   ^^^____
>
> Who is YOU??? I would certainly be requesting the right sectors
> if I (or anybody else who knows what they are doing), wrote
> the boot code. The boot loader knows about OFFSETS into the
> device where it's going to get its data, which eventually
> becomes a whole operating system. It doesn't give a *uck about
> anything else. There is a table of OFFSETS, obtained from
> the file-system, of the correct pieces of files (since there
> will not be a file-system until the machine is booted). This
> table of offsets needs to be read somewhere in the first 63
> sectors (32256 bytes). These offsets contain the junk to
> be loaded into memory.
>
> The boot-code, the code that executes in the 16-bit environment,
> converts those offsets (after getting data from the DPB) into
> the respective junk to put into the registers as I explained
> over and over and over again.
>
> You refuse to learn. Please go away.
>
> [SNIPPED...]
>
> Cheers,
> Dick Johnson
> Penguin : Linux version 2.6.15.4 on an i686 machine (5589.53 BogoMips).
> Warning : 98.36% of all statistics are fiction.
> _
> 
>
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