Re: Installer: no option to set geometry/corrupts partition table

["Simon 'corecode' Schubert" <corecode@xxxxxxxxxxxx>]

On 05.03.2007, at 04:04, randux@noreply.org wrote:
> It's tangential that modern machines 'don't use' c/h/s; the issue is 
> that the partition table is designed around c/h/s values and that's 
> how space gets allocated. When you use fdisk you can certainly 
> allocate things in terms of tracks or cyls or megs or what have you, 
> but the partition table contains c/h/s values and the map is built 
> around this geometry. There's no other common point of control for 
> multiple OS coexistence; how else can partition boundaries be 
> respected?

There is simply *no way* to address more than 8 GB with CHS.  After 
that you're simply out of bits.  You have two options after that:  
either fill all bits with ones to mark that you reached this limit, or 
you simply don't care about the additional bits and wrap around the 
values.

What is the result of this?  You *have* to use logical block 
addressing.  And really, once you're there, you can't care less about 
CHS values and alignment anymore.

However, I do agress that changing existing table values is a really 
bad thing, so the installer shouldn't do this in any case.

> All the other BSDs installers make provisions for preventing 
> this...that being the case, I don't understand the skepticism or the 
> surprise! It hardly seems reasonable that all these other variants 
> make a provision to deal with an issue that is obsolete or irrelevant. 
> Rather, it seems extremely critical. If I understand correctly that 
> the DFly installer was taken from the FreeBSD installer, then I am 
> hoping it will be a very  simple matter to add the G option to DFly's 
> installer.

No, you are mistaken.  The DragonFly installer is really the 
BSDinstaller, but a rather oldish version.  Possibly you mistake the 
source of scepticism.  We're just too few people to do everything 
people could possibly need.  If you want to fix this issue, please go 
ahead!  We appreciate every helping hand!

cheers
  simon

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