[Mageia-dev] Questions on dualbooting/grub/bootloader-utils

Fri Jan 18 13:06:00 CET 2013

Hi...
+
+I have a curious problem...
+I have a box with tow drives, the first one has Windows7 and the second
+Mageia Cauldron.
+I tweaked the W7 bootloader to add an entry for the second drive with EasyBCD
+(it gets wrong the hd1,1 part for its grub entry, it shoud be hd1,0, but that
+is another story...).
+
+I can boot Mageia from W7 bootloader, so my linux disk is sdb, and win
+is sda. Root is right as it should be, /dev/sdb1:
+
+direwolf:~# lsscsi
+[0:0:0:0]    cd/dvd  HL-DT-ST DVD-RAM GH22NP20 2.00  /dev/sr0
+[2:0:0:0]    disk    ATA      ST3400833AS      3.AA  /dev/sda
+[3:0:0:0]    disk    ATA      ST3250310AS      3.AA  /dev/sdb
+
+direwolf:~# df
+Filesystem     Type      Size  Used Avail Use% Mounted on
+rootfs         rootfs    244G  6.1G  226G   3% /
+devtmpfs       devtmpfs  1.6G     0  1.6G   0% /dev
+tmpfs          tmpfs     1.6G   87k  1.6G   1% /dev/shm
+tmpfs          tmpfs     1.6G  877k  1.6G   1% /run
+/dev/sdb1      ext4      244G  6.1G  226G   3% /
+tmpfs          tmpfs     1.6G     0  1.6G   0% /sys/fs/cgroup
+tmpfs          tmpfs     1.6G   13k  1.6G   1% /tmp
+/dev/sda2      fuseblk   400G  134G  267G  34% /media/win
+
+I rewrote GRUBs device.map like:
+
+(hd0) /dev/sda
+(hd1) /dev/sdb
+
+and menu.lst to use (hd1,0) as root.
+
+But every time I install/update a kernel, GRUBs files get rewritten to invert
+the disk mapping, so (hd0) is sdb, and menu.lst changed to boot from (hd0,0),
+and install.sh to write grub on hd0.
+But that settings do no work on boot, after EasyBCD chainloads to second drive,
+it is still the _second_ drive...and grub runs to hd0 to look for kernel/initrd...
+AFAIK, the map hd0->sdb is only usefull for grub installation, once the boot
+sector is stored it is just something like 'ask bios which is the first drive',
+so it fails.
+
+Why do bootloader-utils (I think?) change device.map, menu.lst settings ?
+Why forces the boot disk to be always hd0 ?
+Is there anyway to tell them I dont want to change anything ?
+
+TIA
+
+PD: is there an easier way to tell 'boot from the second drive' in the
+Win7 boot menu than using EasyBCD (I think it is doing some things not so well,
+like numbering first partition in second drive as hd1,1 instead of hd1,0...).
+
+-- 
+J.A. Magallon <jamagallon()ono!com>        \               Winter is coming...
+