On Tue, Oct 03, 2017 at 11:57:06AM -0500, Bruce Dubbs wrote:
> I have been having a problem with fdisk on old computers.
>
> What I am doing is installing Debian, but dropping to the command line and
> creating a GPT manually because Debian seems to want to always create a
> msdos partition table.
>
> After creating the GPT and partitioning, the install proceeds normally, but
> upon reboot the old bios tells me "No bootable disk".
>
> I can fix this by going into rescue mode and setting the pmbr_boot flag
> using parted.
>
> My question is whether this can be done in fdisk. If not, can it be added?
>
> I did try going into expert mode and selecting "toggle the legacy BIOS
> bootable flag", but does not seem to work. I did not see any change to the
> boot sector when using 'd: print the raw data of the first sector from the
> device'.
The tricky thing is that fdisks by default see GPT partition, so you
have to force the tools to ignore GPT and use PMBR. There is more
ways:
1) you can force fdisk to see only MBR and ignore GPT
fdisk --type dos <device>
than you can use fdisk as usually for MBR.
2) start fdisk as usually
- go to expert mode ('r')
- see help ('m')
- switch to nested label ('M')
- go to main menu ('r')
- toggle boot flag ('a')
- write ('w')
3) use sfdisk:
sfdisk --label-nested dos --activate /dev/sda 1
to set boot flag on the first partition.
IMHO 3) is your friend if you have sfdisk :-)
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
http://karelzak.blogspot.com
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