Re: Bug in EZ-Drive remapping code (ide.c)

[Andre Hedrick]

Jochen,

I don't really care about Disk Overlays.
However if you can fix it or if Andries can great.

Sorry,

On Fri, 30 Mar 2001, Jochen Hoenicke wrote:

> Hello,
> 
> The EZ-Drive remapping code remaps to many sectors, if they are read
> together with sector 0 in one bunch.  This is even documented:
> 
> >From linux-2.4.0/drivers/ide/ide.c line 1165:
> /* Yecch - this will shift the entire interval,
>    possibly killing some innocent following sector */
> 
> This problem hit a GRUB user using linux-2.4.2 but it exists for a
> long time; the remapping code is already in 2.0.xx.  The reason that
> nobody cares is probably because there are only a few programs that
> access /dev/hda directly.
> 
> GRUB is a boot loader that normally runs under plain BIOS but there is
> also a wrapper to run it under linux and other unixes.  Because it
> shares most code with its BIOS derivate it accesses the disk the hard
> way, reading directly from /dev/hda and interpreting the file system
> with its own (read-only) file system drivers.
> 
> This is what happened: Grub reads the first track in one bunch and
> since a track has an odd number of sectors, linux adds the first
> sector of the next track to this bunch.  This sector contains the boot
> sector of the first FAT partition.  The result of the remapping is
> that grub can't access that partition.
> 
> Please CC me on reply.
> 
>   Jochen
> 

Andre Hedrick
Linux ATA Development