Re: IDE HPA

[Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>]

On 8/30/05, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> On Maw, 2005-08-30 at 18:16 +0200, Bartlomiej Zolnierkiewicz wrote:
> > HPA shouldn't be disabled by default and new kernel parameter ("hdx=hpa")
> > should be added for disabling HPA (yep, people with buggy BIOS-es will
> > have to add this parameter to their kernel command line, sorry).
> 
> Thats large numbers of systems. Large numbers of disks as strapped for
> 32GB and other clipping arrangements. With a vendor hat on thats
> unworkable because
> 
> a) It will stop thousands of people installing their systems
> b) Many users will get horrible corruption when they update the kernel
> and their box explodes as the fs tries to write to areas of disk that
> have vanished mysteriously.
> 
> (and we know all about this because ancient kernels had options for
> doing this in the compile that burned people)
> 
> So its a very bad idea indeed. A boot option for not disabling the hpa
> is possibly sensible for a few users who want that, or simply getting
> them to fix their buggy user space app would be even simpler.

OK, boot option for disabling HPA for users that want it is a indeed most
sensible approach.

> The only way I can see to truely automate it for most cases would be to
> snoop the partition table if its MSDOS format and see if the table
> matches the HPA clipped disk or the non-HPA clipped disk. If it matches
> the HPA clipped disk then you know not to fiddle. Otherwise its either a
> new disk, clipped by the 32GB jumper, non-x86 disk etc in which case you
> might as well disable any HPA.
> 
> Alan