Syslinux - Jan 2014 - syslinux and btrfs-formatted dos/MBR partition

Hello Gene, thanks for your reply.

Yes BIOS mode. The config wants a menu, which loads fine under ext4
and not under btrfs. Under btrfs I have also tried to remove the
syslinux.cfg file altogether (which should trigger the boot: prompt if
I am not mistaken) and the result is the same: only the copyright line
appears and no prompt.

The three letter sequence is EDD.

The disk is 160GB, here is the fdisk. Tried to install on /dev/sda6
and /dev/sda3.

Disk /dev/sda: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders, total 312581808 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x92e4538c

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1              63   167750729    83875333+   7  HPFS/NTFS/exFAT
/dev/sda2       167750791   296093695    64171452+   f  W95 Ext'd (LBA)
/dev/sda3   *   296094015   312496379     8201182+  83  Linux
/dev/sda4       312496380   312576704       40162+  ef  EFI (FAT-12/16/32)
/dev/sda5       167750793   259915634    46082421    7  HPFS/NTFS/exFAT
/dev/sda6       259917824   296093695    18087936   83  Linux

It's true I am normally chainloading my Linux installations from the
WinXP bootloader, and that is what I initially tried with my btrfs
attempts, however in the course of testing I just backed up my MBR and
let syslinux overwrite it (yes I did set the boot flag before
installing syslinux and overwriting the MBR). That didn't make any
difference.

I am not performing any extra steps (although I tried adding hooks etc
but it didn't work). Simply put, if I follow the Arch wiki step by
step and format with ext4, everything works as expected. If I do the
same with btrfs, it's a no-no.

On 21/01/2014, Gene Cumm <gene.cumm at gmail.com>
wrote:
> On Tue, Jan 21, 2014 at 2:53 AM, David de Marneffe
> <daviddemarneffe at gmail.com> wrote:
>> Hello syslinux list,
>>
>> I have installed Arch over a btrfs-formatted dos/MBR primary
>> partition* (no btrfs subvolumes, just installing everything including
>> /boot in the root of the btrfs).
>>
>> I have been unsuccessful for several days trying to get it to boot
>> with syslinux (6.02-8 package from Arch, also tried 4.07-1  Arch
>> package). All I am getting is the copyright header line and a blinking
>> cursor without keyboard control (can't type). No boot: prompt, no
>> menu, no response to CTRL-ALT-DEL (have to power off to reboot).
>
> So BIOS-mode boot.  If your config wants a menu (likely "UI
menu.c32"
> or the like), you will never see a prompt unless it fails to load.
>
>> I am following the steps in Arch's beginner wiki and their syslinux
>> page (tried both the script provided by Arch and the manual method).
>> When I do this over ext4, everything works as expected, the copyright
>> line appears briefly then the menu pops up. No go with btrfs no matter
>> what I tried. So either it's a bug, or maybe I am repeatedly
missing a
>> step?
>
> What 3-4 letter sequence do you see that indicates its disk access
> mode?  It should be CHS or EDD.
>
>> It looks to me like the ldlinux.sys code embedded in the first 64k of
>> the btrfs partition crashes but no error message is generated. I have
>> dd-ed
>> the first 64k of the btrfs partition and compared the file in a hex
>> editor with the ldlinux.sys file from an ext4 installation, and while
>> no exactly identical it seems to me that ldlinux.sys gets correctly
>> embedded as expected and does not overflow beyond the first 64k.
>
> It won't be identical as the chunks are in differing volume offsets
> and as a result the map and checksum differ.
>
> How big is this disk?  Where is the beginning address?  Are you
> installing a new MBR?  Are you doing any other steps outside those on
> the wiki?
>
>> Any insight would be appreciated. I have been advised to talk to
>> Raphael_sc on irc about it, but I haven't managed to get a hold of
him
>> so far.
>
> The only person I recall getting that advice was attempting to
> chainload from Windows to a btrfs volume.
>
>> * I am not using gpt because I want dual boot with winXP.
>
> This should be OK as long as you're under the 2TiB limit on total disk
> size and your BIOS cooperates.
>
> --
> -Gene
> _______________________________________________
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> Submissions to Syslinux at zytor.com
> Unsubscribe or set options at:
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> Please do not send private replies to mailing list traffic.
>
>

On Tue, Jan 21, 2014 at 7:42 AM, David de Marneffe
<daviddemarneffe at gmail.com> wrote:
> Hello Gene, thanks for your reply.
>
> Yes BIOS mode. The config wants a menu, which loads fine under ext4
> and not under btrfs. Under btrfs I have also tried to remove the
> syslinux.cfg file altogether (which should trigger the boot: prompt if
> I am not mistaken) and the result is the same: only the copyright line
> appears and no prompt.
>
> The three letter sequence is EDD.
Thanks.
> The disk is 160GB, here is the fdisk. Tried to install on /dev/sda6
> and /dev/sda3.
>
> Disk /dev/sda: 160.0 GB, 160041885696 bytes
> 255 heads, 63 sectors/track, 19457 cylinders, total 312581808 sectors
> Units = sectors of 1 * 512 = 512 bytes
> Sector size (logical/physical): 512 bytes / 512 bytes
> I/O size (minimum/optimal): 512 bytes / 512 bytes
> Disk identifier: 0x92e4538c
>
>    Device Boot      Start         End      Blocks   Id  System
> /dev/sda1              63   167750729    83875333+   7  HPFS/NTFS/exFAT
> /dev/sda2       167750791   296093695    64171452+   f  W95 Ext'd (LBA)
> /dev/sda3   *   296094015   312496379     8201182+  83  Linux
> /dev/sda4       312496380   312576704       40162+  ef  EFI (FAT-12/16/32)
> /dev/sda5       167750793   259915634    46082421    7  HPFS/NTFS/exFAT
> /dev/sda6       259917824   296093695    18087936   83  Linux
>
> It's true I am normally chainloading my Linux installations from the
> WinXP bootloader, and that is what I initially tried with my btrfs
> attempts, however in the course of testing I just backed up my MBR and
> let syslinux overwrite it (yes I did set the boot flag before
> installing syslinux and overwriting the MBR). That didn't make any
> difference.
Which MBR?  How did you install it?  The common Microsoft one can not
boot a non-primary partition but the Syslinux mbr.bin and altmbr.bin
can.

-- 
-Gene

A: Because it messes up the order in which people normally read text,
especially the archives of mailing lists.
Q: Why is Top-posting such a bad thing?

"No one ever says, 'I can't read that ASCII(plain text) e-mail you
sent me.'"

For the MBR: I usually don't touch the Microsoft MBR and chainload
Linux from the Microsoft bootloader. However while trying to get my
btrfs setup to work, I backed up the Microsoft MBR (dd if=/dev/sda
bs=440 count=1 of=MBRbackup.bin) and I installed the syslinux MBR. I
tried several ways:
- with the script provided by Arch: syslinux-install_update -i -a -m
- manual method with mbr.bin (first setting the boot flag on
/dev/sda3): dd if=/usr/lib/syslinux/bios/mbr.bin bs=440 count=1
of=/dev/sda
- manual method with altmbr.bin: printf '\x3' | cat
/usr/lib/syslinux/bios/altmbr.bin - | dd bs=440 count=1
iflag=fullblock conv=notrunc of=/dev/sda

No luck any way. Then I just restored the Microsoft MBR.

On 22/01/2014, Gene Cumm <gene.cumm at gmail.com>
wrote:
> On Tue, Jan 21, 2014 at 7:42 AM, David de Marneffe
> <daviddemarneffe at gmail.com> wrote:
>> Hello Gene, thanks for your reply.
>>
>> Yes BIOS mode. The config wants a menu, which loads fine under ext4
>> and not under btrfs. Under btrfs I have also tried to remove the
>> syslinux.cfg file altogether (which should trigger the boot: prompt if
>> I am not mistaken) and the result is the same: only the copyright line
>> appears and no prompt.
>>
>> The three letter sequence is EDD.
>
> Thanks.
>
>> The disk is 160GB, here is the fdisk. Tried to install on /dev/sda6
>> and /dev/sda3.
>>
>> Disk /dev/sda: 160.0 GB, 160041885696 bytes
>> 255 heads, 63 sectors/track, 19457 cylinders, total 312581808 sectors
>> Units = sectors of 1 * 512 = 512 bytes
>> Sector size (logical/physical): 512 bytes / 512 bytes
>> I/O size (minimum/optimal): 512 bytes / 512 bytes
>> Disk identifier: 0x92e4538c
>>
>>    Device Boot      Start         End      Blocks   Id  System
>> /dev/sda1              63   167750729    83875333+   7  HPFS/NTFS/exFAT
>> /dev/sda2       167750791   296093695    64171452+   f  W95 Ext'd
(LBA)
>> /dev/sda3   *   296094015   312496379     8201182+  83  Linux
>> /dev/sda4       312496380   312576704       40162+  ef  EFI
>> (FAT-12/16/32)
>> /dev/sda5       167750793   259915634    46082421    7  HPFS/NTFS/exFAT
>> /dev/sda6       259917824   296093695    18087936   83  Linux
>>
>> It's true I am normally chainloading my Linux installations from
the
>> WinXP bootloader, and that is what I initially tried with my btrfs
>> attempts, however in the course of testing I just backed up my MBR and
>> let syslinux overwrite it (yes I did set the boot flag before
>> installing syslinux and overwriting the MBR). That didn't make any
>> difference.
>
> Which MBR?  How did you install it?  The common Microsoft one can not
> boot a non-primary partition but the Syslinux mbr.bin and altmbr.bin
> can.
>
> --
> -Gene
>
> A: Because it messes up the order in which people normally read text,
> especially the archives of mailing lists.
> Q: Why is Top-posting such a bad thing?
>
> "No one ever says, 'I can't read that ASCII(plain text) e-mail
you sent
> me.'"
> _______________________________________________
> Syslinux mailing list
> Submissions to Syslinux at zytor.com
> Unsubscribe or set options at:
> http://www.zytor.com/mailman/listinfo/syslinux
> Please do not send private replies to mailing list traffic.
>
>