[syslinux] [PATCH] : Adding dlabel option to chain.c32

[Erwan Velu]

That is perfectly true. I had a beautiful bug in the code .... Switching
from python to C have some weird side-effect. Indenting is not enough,
brackets are required....

So I pushed
https://github.com/ErwanAliasr1/syslinux/commit/5a122d218553a6d4019273653ba9fad66d6ae79e
with the fix.
I tested it on my multi-disk system with success.

I also changed the name of the function.

2016-07-17 8:21 GMT+02:00 poma <pomidorabelisima at gmail.com>:

> On 16.07.2016 10:39, Erwan Velu wrote:
> > The idea is to boot a disk in an mbr fashion while using the GPT (not
> > filesystem) label to detect the disk.
> >
> > That is useful when you use grub2 & gpt. I was in case where my nodes
> > (100s) have 8 disks each and no guarantee of which disk is "bootable" in
> > the disk.
> >
> > This way I can tell "please boot the disk that have one partition
> labelled
> > "xyz"".
> >
> > So nothing related to filesystem but gpt labels & disks.
> >
>
>
> For comparison - option "label" - GPT Partition name selection,
> working as expected
>
> SeaBIOS / SYSLINUX
>
> # gdisk -l /dev/vdc
> ...
> Partition table scan:
>   MBR: protective
>   BSD: not present
>   APM: not present
>   GPT: present
>
> Found valid GPT with protective MBR; using GPT.
> Disk /dev/vdc: ...
> ...
> Number  Start (sector)    End (sector)  Size       Code  Name
>    1            2048            6143   2.0 MiB     EF02  BIOS_Boot
>    2          411648         1435647   500.0 MiB   8300  GPT_Boot
>    3         1435648        22646783   10.1 GiB    8300  GPT_Root
>    4        22646784        25163775   1.2 GiB     8200  GPT_Swap
>
>
> boot: chain label=GPT_Boot
> OK
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> As opposed to "label",
> "dlabel" ...
> https://github.com/ErwanAliasr1/syslinux/commit/ebf8cbf
>
> SeaBIOS / GRUB2
>
>     ...
>       ...
>       <target dev='vdc' bus='virtio'/>
>       <boot order='3'/>
>       ...
>       ...
>       <target dev='vdd' bus='virtio'/>
>       <boot order='4'/>
>       ...
>     ...
>
>
> # gdisk -l /dev/vdc
> ...
> Partition table scan:
>   MBR: protective
>   BSD: not present
>   APM: not present
>   GPT: present
>
> Found valid GPT with protective MBR; using GPT.
> Disk /dev/vdc: ...
> ...
> Number  Start (sector)    End (sector)  Size       Code  Name
>    1            2048            6143   2.0 MiB     EF02  BIOS_Boot
>    2          411648         1435647   500.0 MiB   8300  GPT_Boot
>    3         1435648        22646783   10.1 GiB    8300  GPT_Root
>    4        22646784        25163775   1.2 GiB     8200  GPT_Swap
>
>
>
> # gdisk -l /dev/vdd
> ...
> Partition table scan:
>   MBR: protective
>   BSD: not present
>   APM: not present
>   GPT: present
>
> Found valid GPT with protective MBR; using GPT.
> Disk /dev/vdd: ...
> ...
> Number  Start (sector)    End (sector)  Size       Code  Name
>    1            2048            6143   2.0 MiB     EF02  BIOS_Boot_2
>    2          411648         1435647   500.0 MiB   8300  GPT_Boot_2
>    3         1435648        22646783   10.1 GiB    8300  GPT_Root_2
>    4        22646784        25163775   1.2 GiB     8200  GPT_Swap_2
>
>
>
> /boot/extlinux/extlinux.conf
> ...
> label localboot
>   com32 chain.c32
>   append dlabel=GPT_Root
>
> label localboot 2
>   com32 chain.c32
>   append dlabel=GPT_Root_2
> ...
>
> OR
> boot: chain dlabel=GPT_Root
> OR
> boot: chain dlabel=GPT_Root_2
> OR
> boot: chain dlabel=VanillaStrawberry
> OR
> boot: chain dlabel=literallywhateverentered
>
>
> The result is always the same,
> selected for boot is always drive with a higher boot priority,
> in this case - vdc
>
>
>