Re: C/H/S from user space

[linux-os (Dick Johnson)]

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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