[gentoo-user] Change EFI to BIOS Boot

[gentoo-user] Change EFI to BIOS Boot

[Facu Curti]

Hi all. First at all i apologize if my english is not enough.
When I installed gentoo, I do that with UEFI, and gpt partitions. But
right now, I tried to install XEN, and this not works with EFI. I cant
wait until somebody fix this problem, So i'm thinking to change "EFI" to
"BIOS" boot.

So, I deleted the efi (/boot/efi) partition, edited make.conf, and deleted
/etc/default/grub.

After that, I made a new partition with bios_grub
flag. As explained in [1]. And reinstalled grub2 (with new flags).
But I can't boot. Anyway, I can boot from a live cd without
efi, so the problem is not in bios.

I can't find the problem. ¿Some ideas?

parted -l /dev/sdb:

Model: ATA KINGSTON SV300S3 (scsi)
Disk /dev/sdb: 120GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: 

Numero  Inicio  Fin     Tamaño  Sistema de ficheros  Nombre  Banderas
 1      1049kB  11,5MB  10,5MB                               bios_grub
 2      58,7MB  24,8GB  24,7GB  ext4                 rootfs  arranque
 3      24,8GB  28,8GB  3999MB  linux-swap(v1)       swap
 4      28,8GB  120GB   91,2GB  ext4                 home

I made install with:
grub2-install --target=i386-pc --recheck --debug /dev/sdb
grub2-mkconfig /boot/grub/grub.cfg

Thank you in advance list! Bytes! ;)

[1]https://bbs.archlinux.org/viewtopic.php?id=168580

Re: [gentoo-user] Change EFI to BIOS Boot

[Michael Hampicke]

[-- Attachment #1: Type: text/plain, Size: 1590 bytes --]

Am 12.04.2014 12:45, schrieb Facu Curti:
> Hi all. First at all i apologize if my english is not enough.
> When I installed gentoo, I do that with UEFI, and gpt partitions. But
> right now, I tried to install XEN, and this not works with EFI. I cant
> wait until somebody fix this problem, So i'm thinking to change "EFI" to
> "BIOS" boot.
> 
> So, I deleted the efi (/boot/efi) partition, edited make.conf, and deleted
> /etc/default/grub.
> 
> After that, I made a new partition with bios_grub
> flag. As explained in [1]. And reinstalled grub2 (with new flags).
> But I can't boot. Anyway, I can boot from a live cd without
> efi, so the problem is not in bios.
> 
> I can't find the problem. ¿Some ideas?
> 
> parted -l /dev/sdb:
> 
> Model: ATA KINGSTON SV300S3 (scsi)
> Disk /dev/sdb: 120GB
> Sector size (logical/physical): 512B/512B
> Partition Table: gpt
> Disk Flags: 
> 
> Numero  Inicio  Fin     Tamaño  Sistema de ficheros  Nombre  Banderas
>  1      1049kB  11,5MB  10,5MB                               bios_grub
>  2      58,7MB  24,8GB  24,7GB  ext4                 rootfs  arranque
>  3      24,8GB  28,8GB  3999MB  linux-swap(v1)       swap
>  4      28,8GB  120GB   91,2GB  ext4                 home
> 

looks good

> I made install with:
> grub2-install --target=i386-pc --recheck --debug /dev/sdb

Try booting from the live cd and chroot into your gentoo installation.
Reinstall grub from there



> grub2-mkconfig /boot/grub/grub.cfg
> 

Is this a typo? The correct command is

grub2-mkconfig -o /boot/grub/grub.cfg



[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 490 bytes --]

Re: [gentoo-user] Change EFI to BIOS Boot

[Facu Curti]

On Sat, Apr 12, 2014 at 01:06:57PM +0200, Michael Hampicke wrote:
> Am 12.04.2014 12:45, schrieb Facu Curti:
> > Hi all. First at all i apologize if my english is not enough.
> > When I installed gentoo, I do that with UEFI, and gpt partitions. But
> > right now, I tried to install XEN, and this not works with EFI. I cant
> > wait until somebody fix this problem, So i'm thinking to change "EFI" to
> > "BIOS" boot.
> > 
> > So, I deleted the efi (/boot/efi) partition, edited make.conf, and deleted
> > /etc/default/grub.
> > 
> > After that, I made a new partition with bios_grub
> > flag. As explained in [1]. And reinstalled grub2 (with new flags).
> > But I can't boot. Anyway, I can boot from a live cd without
> > efi, so the problem is not in bios.
> > 
> > I can't find the problem. ¿Some ideas?
> > 
> > parted -l /dev/sdb:
> > 
> > Model: ATA KINGSTON SV300S3 (scsi)
> > Disk /dev/sdb: 120GB
> > Sector size (logical/physical): 512B/512B
> > Partition Table: gpt
> > Disk Flags: 
> > 
> > Numero  Inicio  Fin     Tamaño  Sistema de ficheros  Nombre  Banderas
> >  1      1049kB  11,5MB  10,5MB                               bios_grub
> >  2      58,7MB  24,8GB  24,7GB  ext4                 rootfs  arranque
> >  3      24,8GB  28,8GB  3999MB  linux-swap(v1)       swap
> >  4      28,8GB  120GB   91,2GB  ext4                 home
> > 
> 
> looks good
> 
> > I made install with:
> > grub2-install --target=i386-pc --recheck --debug /dev/sdb
> 
> Try booting from the live cd and chroot into your gentoo installation.
> Reinstall grub from there
>
yes, this is what I do. I forgotten mentioning. I'm using sysrescuecd.
> 
> 
> > grub2-mkconfig /boot/grub/grub.cfg
> > 
> 
> Is this a typo? The correct command is
> 
> grub2-mkconfig -o /boot/grub/grub.cfg

Yes, is a typo, im sorry. I do grub2-mkconfig -o /boot/grub/grub.cfg

Thank you for answer!

Re: [gentoo-user] Change EFI to BIOS Boot

[Volker Armin Hemmann]

Am 12.04.2014 12:45, schrieb Facu Curti:

>Partition Table: gpt
:

This

Re: [gentoo-user] Change EFI to BIOS Boot

[Facu Curti]

On Sat, Apr 12, 2014 at 01:23:41PM +0200, Volker Armin Hemmann wrote:
> Am 12.04.2014 12:45, schrieb Facu Curti:
> 
> >Partition Table: gpt
> :
> 
> This
> 
>

This is why I made a bios_grub partition, according this link [1]


[1]https://bbs.archlinux.org/viewtopic.php?id=168580

Re: [gentoo-user] Change EFI to BIOS Boot

[Tom H]

On Sat, Apr 12, 2014 at 6:45 AM, Facu Curti <facu.curti@gmail.com> wrote:


> Hi all. First at all i apologize if my english is not enough.
> When I installed gentoo, I do that with UEFI, and gpt partitions. But
> right now, I tried to install XEN, and this not works with EFI. I cant
> wait until somebody fix this problem, So i'm thinking to change "EFI" to
> "BIOS" boot.
>
> So, I deleted the efi (/boot/efi) partition, edited make.conf, and deleted
> /etc/default/grub.
>
> After that, I made a new partition with bios_grub
> flag. As explained in [1]. And reinstalled grub2 (with new flags).
> But I can't boot. Anyway, I can boot from a live cd without
> efi, so the problem is not in bios.

Did you enable BIOS compatibility mode in the firmware?

Different firmwares have different names for this but a common one is
CSM (compatibility support module).


> I can't find the problem. ¿Some ideas?
>
> parted -l /dev/sdb:
>
> Model: ATA KINGSTON SV300S3 (scsi)
> Disk /dev/sdb: 120GB
> Sector size (logical/physical): 512B/512B
> Partition Table: gpt
> Disk Flags:
>
> Numero  Inicio  Fin     Tamaño  Sistema de ficheros  Nombre  Banderas
>  1      1049kB  11,5MB  10,5MB                               bios_grub
>  2      58,7MB  24,8GB  24,7GB  ext4                 rootfs  arranque
>  3      24,8GB  28,8GB  3999MB  linux-swap(v1)       swap
>  4      28,8GB  120GB   91,2GB  ext4                 home
>
> I made install with:
> grub2-install --target=i386-pc --recheck --debug /dev/sdb
> grub2-mkconfig /boot/grub/grub.cfg

It's "grub2-mkconfig -o /boot/grub/grub.cfg".

Re: [gentoo-user] Change EFI to BIOS Boot

[Tom H]

On Sat, Apr 12, 2014 at 7:23 AM, Volker Armin Hemmann
<volkerarmin@googlemail.com> wrote:
> Am 12.04.2014 12:45, schrieb Facu Curti:
>>
>> Partition Table: gpt
>
> :
> This

You can have a gpt partition table with BIOS but if you want to boot
from that disk, you need a bios_boot partition (which the OP has) for
grub to embed a binary.

Re: [gentoo-user] Change EFI to BIOS Boot

[Facu Curti]

[-- Attachment #1: Type: text/plain, Size: 1962 bytes --]

On Sat, Apr 12, 2014 at 08:16:46AM -0400, Tom H wrote:
> On Sat, Apr 12, 2014 at 6:45 AM, Facu Curti <facu.curti@gmail.com> wrote:
> 
> 
> > Hi all. First at all i apologize if my english is not enough.
> > When I installed gentoo, I do that with UEFI, and gpt partitions. But
> > right now, I tried to install XEN, and this not works with EFI. I cant
> > wait until somebody fix this problem, So i'm thinking to change "EFI" to
> > "BIOS" boot.
> >
> > So, I deleted the efi (/boot/efi) partition, edited make.conf, and deleted
> > /etc/default/grub.
> >
> > After that, I made a new partition with bios_grub
> > flag. As explained in [1]. And reinstalled grub2 (with new flags).
> > But I can't boot. Anyway, I can boot from a live cd without
> > efi, so the problem is not in bios.
> 
> Did you enable BIOS compatibility mode in the firmware?
> 
> Different firmwares have different names for this but a common one is
> CSM (compatibility support module).
> 

yes. It is enabled. And I can boot from a liveCD without EFI support
(tails). So the problem should be on grub I think.
> 
> > I can't find the problem. ¿Some ideas?
> >
> > parted -l /dev/sdb:
> >
> > Model: ATA KINGSTON SV300S3 (scsi)
> > Disk /dev/sdb: 120GB
> > Sector size (logical/physical): 512B/512B
> > Partition Table: gpt
> > Disk Flags:
> >
> > Numero  Inicio  Fin     Tamaño  Sistema de ficheros  Nombre  Banderas
> >  1      1049kB  11,5MB  10,5MB                               bios_grub
> >  2      58,7MB  24,8GB  24,7GB  ext4                 rootfs  arranque
> >  3      24,8GB  28,8GB  3999MB  linux-swap(v1)       swap
> >  4      28,8GB  120GB   91,2GB  ext4                 home
> >
> > I made install with:
> > grub2-install --target=i386-pc --recheck --debug /dev/sdb
> > grub2-mkconfig /boot/grub/grub.cfg
> 
> It's "grub2-mkconfig -o /boot/grub/grub.cfg".
> 

Yes. It was a typing mistake on email. But I ran the command correctly.
I attach my grub.cfg

Thank you for help!

[-- Attachment #2: grub.cfg --]
[-- Type: text/plain, Size: 4643 bytes --]

#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub2-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
  load_env
fi
if [ "${next_entry}" ] ; then
   set default="${next_entry}"
   set next_entry=
   save_env next_entry
   set boot_once=true
else
   set default="0"
fi

if [ x"${feature_menuentry_id}" = xy ]; then
  menuentry_id_option="--id"
else
  menuentry_id_option=""
fi

export menuentry_id_option

if [ "${prev_saved_entry}" ]; then
  set saved_entry="${prev_saved_entry}"
  save_env saved_entry
  set prev_saved_entry=
  save_env prev_saved_entry
  set boot_once=true
fi

function savedefault {
  if [ -z "${boot_once}" ]; then
    saved_entry="${chosen}"
    save_env saved_entry
  fi
}

function load_video {
  if [ x$feature_all_video_module = xy ]; then
    insmod all_video
  else
    insmod efi_gop
    insmod efi_uga
    insmod ieee1275_fb
    insmod vbe
    insmod vga
    insmod video_bochs
    insmod video_cirrus
  fi
}

if [ x$feature_default_font_path = xy ] ; then
   font=unicode
else
insmod part_gpt
insmod ext2
set root='hd1,gpt2'
if [ x$feature_platform_search_hint = xy ]; then
  search --no-floppy --fs-uuid --set=root --hint-bios=hd1,gpt2 --hint-efi=hd1,gpt2 --hint-baremetal=ahci1,gpt2  f453f88d-a359-4e0d-8586-e0c2600c3b2d
else
  search --no-floppy --fs-uuid --set=root f453f88d-a359-4e0d-8586-e0c2600c3b2d
fi
    font="/usr/share/grub/unicode.pf2"
fi

if loadfont $font ; then
  set gfxmode=auto
  load_video
  insmod gfxterm
  set locale_dir=$prefix/locale
  set lang=en_US
  insmod gettext
fi
terminal_output gfxterm
if sleep --interruptible 0 ; then
  set timeout=10
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/10_linux ###
menuentry 'Gentoo GNU/Linux' --class gentoo --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-f453f88d-a359-4e0d-8586-e0c2600c3b2d' {
	load_video
	insmod gzio
	insmod part_gpt
	insmod ext2
	set root='hd1,gpt2'
	if [ x$feature_platform_search_hint = xy ]; then
	  search --no-floppy --fs-uuid --set=root --hint-bios=hd1,gpt2 --hint-efi=hd1,gpt2 --hint-baremetal=ahci1,gpt2  f453f88d-a359-4e0d-8586-e0c2600c3b2d
	else
	  search --no-floppy --fs-uuid --set=root f453f88d-a359-4e0d-8586-e0c2600c3b2d
	fi
	echo	'Loading Linux 3.12.13-gentoo ...'
	linux	/boot/kernel-3.12.13-gentoo root=/dev/sdb2 ro  
}
submenu 'Advanced options for Gentoo GNU/Linux' $menuentry_id_option 'gnulinux-advanced-f453f88d-a359-4e0d-8586-e0c2600c3b2d' {
	menuentry 'Gentoo GNU/Linux, with Linux 3.12.13-gentoo' --class gentoo --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-3.12.13-gentoo-advanced-f453f88d-a359-4e0d-8586-e0c2600c3b2d' {
		load_video
		insmod gzio
		insmod part_gpt
		insmod ext2
		set root='hd1,gpt2'
		if [ x$feature_platform_search_hint = xy ]; then
		  search --no-floppy --fs-uuid --set=root --hint-bios=hd1,gpt2 --hint-efi=hd1,gpt2 --hint-baremetal=ahci1,gpt2  f453f88d-a359-4e0d-8586-e0c2600c3b2d
		else
		  search --no-floppy --fs-uuid --set=root f453f88d-a359-4e0d-8586-e0c2600c3b2d
		fi
		echo	'Loading Linux 3.12.13-gentoo ...'
		linux	/boot/kernel-3.12.13-gentoo root=/dev/sdb2 ro  
	}
	menuentry 'Gentoo GNU/Linux, with Linux 3.12.13-gentoo (recovery mode)' --class gentoo --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-3.12.13-gentoo-recovery-f453f88d-a359-4e0d-8586-e0c2600c3b2d' {
		load_video
		insmod gzio
		insmod part_gpt
		insmod ext2
		set root='hd1,gpt2'
		if [ x$feature_platform_search_hint = xy ]; then
		  search --no-floppy --fs-uuid --set=root --hint-bios=hd1,gpt2 --hint-efi=hd1,gpt2 --hint-baremetal=ahci1,gpt2  f453f88d-a359-4e0d-8586-e0c2600c3b2d
		else
		  search --no-floppy --fs-uuid --set=root f453f88d-a359-4e0d-8586-e0c2600c3b2d
		fi
		echo	'Loading Linux 3.12.13-gentoo ...'
		linux	/boot/kernel-3.12.13-gentoo root=/dev/sdb2 ro single 
	}
}

### END /etc/grub.d/10_linux ###

### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###

### BEGIN /etc/grub.d/30_os-prober ###
### END /etc/grub.d/30_os-prober ###

### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###

### BEGIN /etc/grub.d/41_custom ###
if [ -f  ${config_directory}/custom.cfg ]; then
  source ${config_directory}/custom.cfg
elif [ -z "${config_directory}" -a -f  $prefix/custom.cfg ]; then
  source $prefix/custom.cfg;
fi
### END /etc/grub.d/41_custom ###

[gentoo-user] Re: Change EFI to BIOS Boot

[walt]

On 04/12/2014 03:45 AM, Facu Curti wrote:
> Hi all. First at all i apologize if my english is not enough.
> When I installed gentoo, I do that with UEFI, and gpt partitions. But
> right now, I tried to install XEN, and this not works with EFI. I cant
> wait until somebody fix this problem, So i'm thinking to change "EFI" to
> "BIOS" boot.
> 
> So, I deleted the efi (/boot/efi) partition, edited make.conf, and deleted
> /etc/default/grub.
> 
> After that, I made a new partition with bios_grub
> flag. As explained in [1]. And reinstalled grub2 (with new flags).
> But I can't boot.

What happens when you try to boot?  Can you see the grub2 menu screen?

If you can see the grub2 menu screen you should try using the grub2
command shell (type "c" to enter the command shell) which will allow
you to experiment with all of the grub commands that you compiled into
the grub2 package.

If you can get to the grub shell prompt you can hit TAB to see a list of
available grub commands.

The important point is this:  any grub command that works from the grub
shell prompt can be typed *verbatim* into a grub2 'menuitem' stanza.

The first time I used grub2-mkconfig I noticed that it generates config
files that strike me as a bit hysterical (excuse the sexist adjective).

[gentoo-user] Re: Change EFI to BIOS Boot

[Jonathan Callen]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA512

On 04/12/2014 08:19 AM, Tom H wrote:
> On Sat, Apr 12, 2014 at 7:23 AM, Volker Armin Hemmann <volkerarmin@googlemail.com> wrote:
>> Am 12.04.2014 12:45, schrieb Facu Curti:
>>> 
>>> Partition Table: gpt
>> 
>> : This
> 
> You can have a gpt partition table with BIOS but if you want to boot from that disk, you need a
> bios_boot partition (which the OP has) for grub to embed a binary.
> 
> 

Technically, I don't think you need a bios_boot partition if you leave enough space between the
partition table and the first partition (I don't recall having a problem when my first partition
started 2048 sectors (1MiB) into the disk).

- -- 
Jonathan Callen
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.22 (GNU/Linux)
Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/
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=/6My
-----END PGP SIGNATURE-----

Re: [gentoo-user] Re: Change EFI to BIOS Boot

[Facu Curti]

On Sat, Apr 12, 2014 at 06:06:13PM -0700, walt wrote:
> On 04/12/2014 03:45 AM, Facu Curti wrote:
> > Hi all. First at all i apologize if my english is not enough.
> > When I installed gentoo, I do that with UEFI, and gpt partitions. But
> > right now, I tried to install XEN, and this not works with EFI. I cant
> > wait until somebody fix this problem, So i'm thinking to change "EFI" to
> > "BIOS" boot.
> > 
> > So, I deleted the efi (/boot/efi) partition, edited make.conf, and deleted
> > /etc/default/grub.
> > 
> > After that, I made a new partition with bios_grub
> > flag. As explained in [1]. And reinstalled grub2 (with new flags).
> > But I can't boot.
> 
> What happens when you try to boot?  Can you see the grub2 menu screen?
>
No, I cant see grub menu. It just restarts.

I could not fix it, so I'm going to format the computer. I will make a 
backup from system,format as ms_dos, and then restore backup. 
If anyone can give me any sugestion, I will appreciate that.

Thank you all for help. Bytes! ;)

Re: [gentoo-user] Re: Change EFI to BIOS Boot

[Neil Bothwick]

[-- Attachment #1: Type: text/plain, Size: 770 bytes --]

On Sun, 13 Apr 2014 19:21:56 -0300, Facu Curti wrote:

> > > When I installed gentoo, I do that with UEFI, and gpt partitions.
> > > But right now, I tried to install XEN, and this not works with EFI.
> > > I cant wait until somebody fix this problem, So i'm thinking to
> > > change "EFI" to "BIOS" boot.

> I could not fix it, so I'm going to format the computer. I will make a 
> backup from system,format as ms_dos, and then restore backup. 

The partition table format is not the same as the bootloader. It is quite
possible to use GPT partition tables with BIOS firmware, as long as you
have that 1MB partition of type EF02 at the start of the table.


-- 
Neil Bothwick

Never wrestle with a pig. You both get dirty but only the pig enjoys it.

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 198 bytes --]

Re: [gentoo-user] Re: Change EFI to BIOS Boot

[Tom H]

On Sun, Apr 13, 2014 at 11:08 AM, Jonathan Callen <jcallen@gentoo.org> wrote:
> On 04/12/2014 08:19 AM, Tom H wrote:
>>
>> You can have a gpt partition table with BIOS but if you want to boot from that disk, you need a
>> bios_boot partition (which the OP has) for grub to embed a binary.
>
> Technically, I don't think you need a bios_boot partition if you leave enough space between the
> partition table and the first partition (I don't recall having a problem when my first partition
> started 2048 sectors (1MiB) into the disk).

You're correct if you're talking about an msdos-labelled disk with
bios firmware because having the first partition start on 2048 as it
does now rather on 63 as it used to because the post-mbr gap will
always be big enough for grub to embed core.img.

But on a gpt-labelled disk with bios firmware, there's a <something>
mbr into which grub embeds boot.img but there's no post-mbr gap. So a
bios_boot partition's needed in order to embed core.img (IIRC parted
calls it grub_bios or bios_grub).

Re: [gentoo-user] Re: Change EFI to BIOS Boot

[Facundo Curti]

2014-04-19 12:34 GMT-03:00 Tom H <tomh0665@gmail.com>:
> On Sun, Apr 13, 2014 at 11:08 AM, Jonathan Callen <jcallen@gentoo.org> wrote:
>> On 04/12/2014 08:19 AM, Tom H wrote:
>>>
>>> You can have a gpt partition table with BIOS but if you want to boot from that disk, you need a
>>> bios_boot partition (which the OP has) for grub to embed a binary.
>>
>> Technically, I don't think you need a bios_boot partition if you leave enough space between the
>> partition table and the first partition (I don't recall having a problem when my first partition
>> started 2048 sectors (1MiB) into the disk).
>
> You're correct if you're talking about an msdos-labelled disk with
> bios firmware because having the first partition start on 2048 as it
> does now rather on 63 as it used to because the post-mbr gap will
> always be big enough for grub to embed core.img.
>
> But on a gpt-labelled disk with bios firmware, there's a <something>
> mbr into which grub embeds boot.img but there's no post-mbr gap. So a
> bios_boot partition's needed in order to embed core.img (IIRC parted
> calls it grub_bios or bios_grub).
>

As I could not fix it, I solved it making backup, formating with
ms_dos table, and restoring backup. :P