Grub2 documentation of the GRUB_CMDLINE_*XEN* parameters -- unclear. What's _intended_?

Grub2 documentation of the GRUB_CMDLINE_*XEN* parameters -- unclear. What's _intended_?

[PGNet Dev]

Grub2 documentation @ 
https://www.gnu.org/software/grub/manual/grub.html#Configuration states

	...
	‘GRUB_CMDLINE_XEN’
	‘GRUB_CMDLINE_XEN_DEFAULT’

	    The values of these options are appended to the values of 
‘GRUB_CMDLINE_LINUX’ and ‘GRUB_CMDLINE_LINUX_DEFAULT’ for Linux and Xen 
menu entries.
	‘GRUB_CMDLINE_LINUX_XEN_REPLACE’
	‘GRUB_CMDLINE_LINUX_XEN_REPLACE_DEFAULT’

	    The values of these options replace the values of 
‘GRUB_CMDLINE_LINUX’ and ‘GRUB_CMDLINE_LINUX_DEFAULT’ for Linux and Xen 
menu entries.
	...

 From these docs. it's not clear which values get mapped to which grub 
entries.  One set 'appends', one set 'replaces'.  Are they exclusive of 
one another?

And, what specifically gets mapped to Xen kernel's "options=" parameter 
line?

E.g., a grub2-mkconfig-generated xen*.cfg takes the form

	# disclaimer
	[global]
	#default=

	[config.1]
	options= dom0_mem= ...
	kernel=vmlinuz-4.3.0-16.gff1dcd9-xen ...
	ramdisk=initrd-4.3.0-16.gff1dcd9-xen ...

whereas for a NON-xen grub*.cfg

	# disclaimer
	[global]
	#default=

	[config.1]
	kernel=vmlinuz-4.3.0-16.gff1dcd9-default ...
	ramdisk=initrd-4.3.0-16.gff1dcd9-default ...

there's NO "options=..." line.

The docs should clearly address which PARAMETERS map to the "options=" 
line, and which to the kernel=" line in the Xen case.

To get there -- What's intended, by designn, from development in these 
specific *XEN* cases?

Re: Grub2 documentation of the GRUB_CMDLINE_*XEN* parameters -- unclear. What's _intended_?

[Andrei Borzenkov]

22.11.2015 03:12, PGNet Dev пишет:
> Grub2 documentation @
> https://www.gnu.org/software/grub/manual/grub.html#Configuration states
>
>      ...
>      ‘GRUB_CMDLINE_XEN’
>      ‘GRUB_CMDLINE_XEN_DEFAULT’
>
>          The values of these options are appended to the values of
> ‘GRUB_CMDLINE_LINUX’ and ‘GRUB_CMDLINE_LINUX_DEFAULT’ for Linux and Xen
> menu entries.

That's not what current manual says. Please use current upstream sources 
when you contact upstream.

>      ‘GRUB_CMDLINE_LINUX_XEN_REPLACE’
>      ‘GRUB_CMDLINE_LINUX_XEN_REPLACE_DEFAULT’
>
>          The values of these options replace the values of
> ‘GRUB_CMDLINE_LINUX’ and ‘GRUB_CMDLINE_LINUX_DEFAULT’ for Linux and Xen
> menu entries.

I agree it is a bit fuzzy. If set, it is used for Linux kernel arguments 
in Xen menu entries. Care to send a patch clarifying it?

>      ...
>
>  From these docs. it's not clear which values get mapped to which grub
> entries.  One set 'appends', one set 'replaces'.  Are they exclusive of
> one another?
>
> And, what specifically gets mapped to Xen kernel's "options=" parameter
> line?
>
> E.g., a grub2-mkconfig-generated xen*.cfg takes the form
>

Please direct this question to your distribution. For a start, there is 
no grub2-mkconfig upstream.

>      # disclaimer
>      [global]
>      #default=
>
>      [config.1]
>      options= dom0_mem= ...
>      kernel=vmlinuz-4.3.0-16.gff1dcd9-xen ...
>      ramdisk=initrd-4.3.0-16.gff1dcd9-xen ...
>
> whereas for a NON-xen grub*.cfg
>
>      # disclaimer
>      [global]
>      #default=
>
>      [config.1]
>      kernel=vmlinuz-4.3.0-16.gff1dcd9-default ...
>      ramdisk=initrd-4.3.0-16.gff1dcd9-default ...
>

I have no idea what you are talking about, sorry. Again, you need to 
direct this question to your distribution.

> there's NO "options=..." line.
>
> The docs should clearly address which PARAMETERS map to the "options="
> line, and which to the kernel=" line in the Xen case.
>
> To get there -- What's intended, by designn, from development in these
> specific *XEN* cases?
>
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> https://lists.gnu.org/mailman/listinfo/grub-devel

Re: Grub2 documentation of the GRUB_CMDLINE_*XEN* parameters -- unclear. What's _intended_?

[PGNet Dev]

On 11/21/2015 10:37 PM, Andrei Borzenkov wrote:
> That's not what current manual says.

That's exactly what the grub web site says.

> I have no idea what you are talking about, sorry.

That's interesting, as it's Opensuse/ the distro for which you're the 
grub2 maintainer.

Re: Grub2 documentation of the GRUB_CMDLINE_*XEN* parameters -- unclear. What's _intended_?

[Colin Watson]

On Sat, Nov 21, 2015 at 04:12:52PM -0800, PGNet Dev wrote:
> Grub2 documentation @
> https://www.gnu.org/software/grub/manual/grub.html#Configuration states
> 
> 	...
> 	‘GRUB_CMDLINE_XEN’
> 	‘GRUB_CMDLINE_XEN_DEFAULT’
> 
> 	    The values of these options are appended to the values of
> ‘GRUB_CMDLINE_LINUX’ and ‘GRUB_CMDLINE_LINUX_DEFAULT’ for Linux and Xen menu
> entries.
> 	‘GRUB_CMDLINE_LINUX_XEN_REPLACE’
> 	‘GRUB_CMDLINE_LINUX_XEN_REPLACE_DEFAULT’
> 
> 	    The values of these options replace the values of ‘GRUB_CMDLINE_LINUX’
> and ‘GRUB_CMDLINE_LINUX_DEFAULT’ for Linux and Xen menu entries.
> 	...
> 
> From these docs. it's not clear which values get mapped to which grub
> entries.  One set 'appends', one set 'replaces'.  Are they exclusive of one
> another?

No, they aren't exclusive of one another, but are used to construct
different command lines.  GRUB_CMDLINE_XEN* are used for the hypervisor
command line; GRUB_CMDLINE_LINUX_XEN_REPLACE* are used for the Linux
kernel command line (but if unset, the corresponding GRUB_CMDLINE_LINUX*
values are used instead).

The misleading description you quote was the one in 2.00, but was
clarified in git a while ago:

  http://git.savannah.gnu.org/cgit/grub.git/commit/?id=48f39bb4df5b903aaa66db9fdc6679571bff0dd9

> And, what specifically gets mapped to Xen kernel's "options=" parameter
> line?
> 
> E.g., a grub2-mkconfig-generated xen*.cfg takes the form

Upstream grub-mkconfig does not generate xen*.cfg at all.  This is an
openSUSE-specific patch.  From inspecting their source code, I believe
that the GRUB_CMDLINE_XEN* options will apply here.

> The docs should clearly address which PARAMETERS map to the "options=" line,
> and which to the kernel=" line in the Xen case.

No doubt, but it is up to the openSUSE maintainers to make sure that
their patches also include appropriate documentation changes.

-- 
Colin Watson                                       [cjwatson@ubuntu.com]

Re: Grub2 documentation of the GRUB_CMDLINE_*XEN* parameters -- unclear. What's _intended_?

[PGNet Dev]

On 11/22/2015 11:54 AM, Colin Watson wrote:
> No, they aren't exclusive of one another, but are used to construct
> different command lines.  GRUB_CMDLINE_XEN* are used for the hypervisor
> command line; GRUB_CMDLINE_LINUX_XEN_REPLACE* are used for the Linux
> kernel command line (but if unset, the corresponding GRUB_CMDLINE_LINUX*
> values are used instead).
>
> The misleading description you quote was the one in 2.00, but was
> clarified in git a while ago:
>
>    http://git.savannah.gnu.org/cgit/grub.git/commit/?id=48f39bb4df5b903aaa66db9fdc6679571bff0dd9

That's exactly the helpful clarification needed. Thanks!  It'd be useful 
to have that updated on the grub2 website's docs -- it's just as valid 
there.

>> And, what specifically gets mapped to Xen kernel's "options=" parameter
>> line?
>>
>> E.g., a grub2-mkconfig-generated xen*.cfg takes the form

> Upstream grub-mkconfig does not generate xen*.cfg at all.  This is an
> openSUSE-specific patch.  From inspecting their source code, I believe
> that the GRUB_CMDLINE_XEN* options will apply here.

I'd realized that there's different naming, e.g. the "grub2-mkconfig", 
but had not realized this^^ diff as well.

>> The docs should clearly address which PARAMETERS map to the "options=" line,
>> and which to the kernel=" line in the Xen case.
>
> No doubt, but it is up to the openSUSE maintainers to make sure that

Noted.  The latest upgrade of the distro has proven to be quite 
problematic, particularly in the real-world/modern { pv-kernel + Xen + 
Grub2 + EFI } use case; and the docs are a bit of a mess.   I'd 
_strongly_ prefer a grub2 instance closer to upstream's.  Not yet sure 
what replacing the distro's with a 'clean' upstream build entails ...

Thanks again for the response.