For the "map" command to work properly which of the statements below is correct (legacy/mbr computer with two hard disks):
1) Both (hd0,0) and (hd1,0) must start at sector 63
2) If (hd0,0) starts at sector 63 then (hd1,0) must also start at sector 63
3) If (hd0,0) starts at sector 2048 then (hd1,0) must also start at sector 2048
I got into problems with Grub4Dos "map" command when (hd0,0) started at sector 63 and (hd1,0) started at sector 2048. Bart PE installed on (hd1,0) would not boot. Here is "menu.lst":
title Bart PE on Hard Disk #2
map (hd0) (hd1)
map (hd1) (hd0)
Setting the start sector at 63 for both (hd0,0) and (hd1,0) resolved the problem, which might actually be related to Bart PE (it's built from Windows XP SP2) and not Grub4Dos, it's hard to tell.
Initially I bootlaced G4D boot sector code to (hd1,0) and booted from there but this setup was not stable so I bootlaced (hd0,2) and everything works just fine now. My first stage (MBR) bootloader is Boot-US and then I select the partition to boot to with G4D.
Lately I decided to install a new second hard disk and install Bart PE on the hard drive (to get it running faster than from a flash drive). I assumed it was going to be a routine task that would take about one hour to complete, but instead I got into all this mind-boggling stuff about Advanced Format Drives with 4096 byte sectors that emulate 512 byte sectors, partitions aligned to 1 MiB instead of CHS, first primary partition starting at sector 2048 instead of 63, etc. I'm slowly trying to sort this out because when you want to keep using some legacy software there are some conflicting requirements to deal with.
- legacy BIOS / MBR computer
- two new 500 GB hard disks with 4096 / e512 sectors
- 1st stage bootloader (MBR): Boot-US
- 2nd stage bootloader (PBR): Grub4Dos v0.4.5c-2014-12-24
- Bart PE with 2009 Acronis True Image plugin, installed on (hd1,0)
- primary OS: Linux Xubuntu 14.04.1 LTS
- secondary OS: Windows XP SP3
Edited by Kirkx, 11 January 2015 - 08:38 AM.