Re: Possible to boot DOS from UEFI grub?

[Steve]

chainloader (hd2)+1

This does not work if you have booted via UEFI to grub2.
It only works if you have MBR-booted to grub2,

 If you have UEFI-booted then
chainloader (hd2)+1
will always give the error:
error: invalid EFI file path.


On Thu, 28 Feb 2019 at 23:38, Jeff Sadowski <address@hidden> wrote:

> Interesting someone suggested chain-loading
> the MBR version of the boot loader and boot DOS from there.
> Which worked.
>
> I did
> chainloader (hd2)+1
>
> Then I was able to use the DOS menuentry to boot DOS.
>
> On Thu, Feb 28, 2019 at 5:59 PM Steve <address@hidden> wrote:
> >
> > When you UEFI-boot, the CPU is in Long Mode and there is no BIOS support
> (BIOS interrupts are not supported).
> >
> > DOS works in Real Mode and uses BIOS interrupts for kbd, screen and disk
> access, etc.
> >
> > So there is no way you can UEFI-boot to DOS!
> >
> >
> >
> > On Thu, 28 Feb 2019 at 22:52, Jeff Sadowski <address@hidden>
> wrote:
> >>
> >> OK I've been trying a bunch of things here but not having much luck.
> >>
> >> I am familiar with normal booting from UEFI grub and MBR versions of
> grub
> >>
> >> I can boot DOS from Legacy Grub with the following
> >>
> >> grub> root='hd2,msdos1'
> >> grub> parttool ${root} hidden-
> >> Setting partition type to 0x6
> >> grub> drivemap -s (hd0) ${root}
> >> grub> chainloader +1
> >>
> >> If I try this in UEFI grub
> >>
> >> grub> root='hd2,msdos1'
> >> grub> parttool ${root} hidden-
> >> Setting partition type to 0x6
> >> grub> drivemap -s (hd0) ${root}
> >> error: can't find command `drivemap'.
> >> grub> chainloader +1
> >> error: invalid EFI file path.
> >>
> >> If I try and let update-grub fix it They go away completely if I boot
> >> from UEFI mode.
> >>
> >> For now I have resigned to just booting everything from Legacy mode
> >> but would like to know if it is possible to use it from UEFI mode?
> >>
> >> _______________________________________________
> >> Help-grub mailing list
> >> address@hidden
> >> https://lists.gnu.org/mailman/listinfo/help-grub
>