Mapping arcpaths to devicenumbers...

NTFSD
1

Does anyone know a way to reliably map an arcpath’s rdisk(x) value to a
device name (e.g., \device\harddiskx)? On pure IDE machines harddisk0
always maps to rdisk(0), harddisk1 to rdisk(1), etc. However, this is not
always true on mixed ide/scsi machines.

The need arises on two fronts:

  1. creating and deleting partitions can change the partition number of the
    boot (OS) partition.

  2. the boot.ini is a good way to quickly identify systems on a multi-boot
    machine.

Example where the mapping is ambiguos: If \device\harddisk1 contains the
boot.ini, and the system is on \device\harddisk0, then rdisk(0) is
actually harddisk1.

thanks, russ

2

> Does anyone know a way to reliably map an arcpath’s rdisk(x) value
to a

device name (e.g., \device\harddiskx)? On pure IDE machines
harddisk0

Early on boot, NT creates the \ArcName object directory, which
contains the ARC-syntax symlinks to the NT device names.

The creation is done on the following bases:

  • NTLDR have read all boot sector signatures from all disks known to
    it (all int 13h disks or all disks available via NtBootDd.sys).
  • NTLDR passes an array of all ARC names of all known disks together
    with their signatures to the kernel.
  • the kernel also reads these boot sector signatures and matches them
    to the array passed by the NTLDR.
  • by the described matching, the \ArcName object directory is built.
    It is then used to find the \SystemRoot disk.

Max