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

[poma]

On 15.07.2016 17:53, Ady Ady via Syslinux wrote:
> 
>> On 30.06.2016 19:41, Erwan Velu via Syslinux wrote:
>>> The exisiting label= option offer to boot on a gpt partition that have
>>> a particular label.
>>> The existing guuid= option offer to boot on a disk or partition with a
>>> particular label.
>>>
>>> This new option offer to boot the disk that have a partition which
>>> have a given label.
>>> The label is so just a way to detect a disk to boot.
>>>
>>> A typical use is for making an intelligent localboot like :
>>>
>>>     label localboot
>>>         com32 chain.c32
>>>         append dlabel=datapartition
>>>
>>> This allow booting on a disk that sports a least one partition
>>> labelled "datapartition".
>>>
>>> You can consider dlabel= doing almost what mbr= does but by inspecting
>>> the gpt partitions label.
>>>
>>>
>>> Please find below the commit :
>>> https://github.com/ErwanAliasr1/syslinux/commit/ebf8cbfb8cef49517aa36b4a79998b4332289489
>>>
>>
>>
>> # gdisk -l /dev/vda
>> ...
>> Partition table scan:
>>   MBR: protective
>>   BSD: not present
>>   APM: not present
>>   GPT: present
>>
>> Found valid GPT with protective MBR; using GPT.
>> ...
>> Number  Start (sector)    End (sector)  Size       Code  Name
>>    1            2048          411647   200.0 MiB   EF00  EFI System Partition
>>    2          411648         1435647   500.0 MiB   8300  BOOT System Partition
>>    3         1435648        22646783   10.1 GiB    8300  ROOT System Partition
>>    4        22646784        25163775   1.2 GiB     8200  SWAP System Partition
>>
>>
>> # fdisk -l /dev/vda
>> ...
>> Disklabel type: gpt
>> ...
>> Device        Start      End  Sectors  Size Type
>> /dev/vda1      2048   411647   409600  200M EFI System
>> /dev/vda2    411648  1435647  1024000  500M Linux filesystem
>> /dev/vda3   1435648 22646783 21211136 10.1G Linux filesystem
>> /dev/vda4  22646784 25163775  2516992  1.2G Linux swap
>>
>>
>> # fatlabel /dev/vda1 
>> labelefi   
>>
>> # e2label /dev/vda2
>> labelboot
>>
>> # e2label /dev/vda3
>> labelroot
>>
>> # swaplabel /dev/vda4
>> LABEL: labelswap
>> ...
>>
>>
>> Filesystem *label* and *label* of a swap area
>> distinguish from
>> GPT *name* of a partition
>>
>  
>  
> _If_ I understand Erwan's patch correctly, we are talking about the GPT Partition Name, not the 
> filesystem's label (but I could be wrong).
>  
>  
>>
>> Therefore -if- you are referring to a GPT partition *name*,
>> simple *name* as append option - for GPT partition *name* selection, should suffice
>> i.e.
>>   ...
>>   append name=gptpartitionname
>  
>  
> Not exactly. We are distinguishing between the GPT Partition Name being used just to select the 
> next device (for example, your "ROOT System Partition"), and the (Protective) MBR we are jumping 
> to, in BIOS / CSM mode.
> 
> In my prior email I suggested "diskbypartname" with relevant explanations (see 
> http://www.syslinux.org/archives/2016-July/025305.html ).
> 
> Tests and feedback are appreciated.
> 
> Regards,
> Ady.
> 

For once, precise explanation of the author is really required,
afterwards the actual option name should not be a problem

e.g.
append icecream=whicheverflavor
;)