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Ranish Partition Manager revived (Announce)

posted by boeckmann, Aachen, Germany, 19.11.2022, 21:46

> I think both geometries are essentially fictional.
>
> 13.08 is the way to go for things that expect to use CHS access functions,
> because it should match what these functions (13.02 and 13.03) use. This
> includes old loaders and OSes. Therefore this also includes the CHS
> triplets in the MBR partition table entries, as well as the H and S values
> in a FAT FS's BPB. (But note that one controller + ROM-BIOS combo could use
> different geometry than another combo for the same disk.)
>
> The 13.48 function is
> documented as giving a "physical" geometry with three dwords but I
> believe this is mostly fictional as well. It may fit what the controller
> uses or not. In any case, there's an amount of total sectors qword which
> you can use to get the exact size of the disk without any geometry
> calculations. And for the 13.4x functions you do only need the Logical
> Block numbers, and therefore only the total blocks amount, not the
> "physical geometry".
Thanks for the feedback. So it is essentially like I thought it should be. While the geometry is not strictly needed when working with LBA I want to leave the CHS view Ranish provides intact. So I have to calculate the cylinder count from the H and S of 13.08 and the total sectors returned by 13.48 by myself. Of course all relevant source positions have to be verified that the fallen 1024/255/63 CHS barrier does not lead to corrupt CHS entries anywhere on disk. Certainly on many places warning / error messages have to be implemented to inform the user of non-compatible partition locations etc.

I think it is a good idea to make the LBA view the default when operating on disk >8GB but I want to leave the user the option to switch back to CHS view.

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