Re: [GRUB PARTUUID PATCH V9 4/5] Update grub script template files

[Nick Vinson]

On 04/10/2018 01:52 PM, Daniel Kiper wrote:
> On Sat, Apr 07, 2018 at 04:28:13PM -0700, Nicholas Vinson wrote:
>> Update grub-mkconfig.in and 10_linux.in to support grub-probe's new
>> partuuid target.  Update grub.texi documentation.  The following table
>> shows how GRUB_DISABLE_LINUX_UUID, GRUB_DISABLE_LINUX_PARTUUID, and
>> initramfs detection interact:
>>
>> Initramfs  GRUB_DISABLE_LINUX_PARTUUID  GRUB_DISABLE_LINUX_UUID  Linux Root
>> detected   Set                          Set                      ID Method
>>
>> False      False                        False                    part UUID
>> False      False                        True                     part UUID
>> False      True                         False                    dev name
>> False      True                         True                     dev name
>> True       False                        False                    fs UUID
>> True       False                        True                     part UUID
>> True       True                         False                    fs UUID
>> True       True                         True                     dev name
> 
> What will happen if GRUB_DISABLE_LINUX_PARTUUID and/or GRUB_DISABLE_LINUX_UUID
> are not set? I think that you can avoid that by setting defaults. You do that
> for GRUB_DISABLE_LINUX_PARTUUID in next patch but GRUB_DISABLE_LINUX_UUID
> does not have any default.
> 

If they're not set, then that's the same as them being set to 'False'.
I should have worded my table above a bit differently and used Yes/No
instead of True/False as that is really what it is trying to convey.
I.E. If there is no initramfs detected and GRUB_DISABLE_LINUX_PARTUUID
is not set and GRUB_DISABLE_LINUX_UUID is not set, set the kernel root
variable to "root=PARTUUID=...".

In the scripts, the only value explicitly checked for is 'true'.
Anything else (including unset) is considered false.

>> Signed-off-by: Nicholas Vinson <address@hidden>
>> ---
>>  docs/grub.texi          | 10 ++++++++++
>>  util/grub-mkconfig.in   |  3 +++
>>  util/grub.d/10_linux.in | 18 +++++++++++++++---
> 
> Could you update util/grub.d/20_linux_xen.in too?

Let me see what I can do.  I have never worked with xen before, so I do
not know much about it.

> 
>>  3 files changed, 28 insertions(+), 3 deletions(-)
>>
>> diff --git a/docs/grub.texi b/docs/grub.texi
>> index 65b4bbeda..06f0afe45 100644
>> --- a/docs/grub.texi
>> +++ b/docs/grub.texi
>> @@ -1424,6 +1424,16 @@ the Linux kernel, using a @samp{root=UUID=...} kernel 
>> parameter.  This is
>>  usually more reliable, but in some cases it may not be appropriate.  To
>>  disable the use of UUIDs, set this option to @samp{true}.
>>
>> address@hidden GRUB_DISABLE_LINUX_PARTUUID
>> +If @command{grub-mkconfig} cannot identify the root filesystem via its
>> +universally-unique indentifier (UUID), @command{grub-mkconfig} will use the 
>> UUID
>> +of the partition containing the filesystem to identify the root filesystem 
>> to
>> +the Linux kernel via a @samp{root=PARTUUID=...} kernel parameter.  This is 
>> not
>> +as reliable as using the filesystem UUID, but is more reliable than using 
>> the
>> +Linux device names.  When enabled, this option requires the Linux kernel 
>> version
> 
> s/When enabled, /When enabled, GRUB_DISABLE_LINUX_PARTUUID set to false, /
> or something like that. Otherwise it is unclear.

I'll clean up the wording in the next release.

Thanks,
Nicholas Vinson

> 
> Daniel
>