Re: [PATCH v5] probe: Support probing for GPT partition UUID with -g

[Jacob Kroon]

Hi Didier,

On Mon, May 13, 2019 at 10:53 PM Didier Spaier <address@hidden> wrote:
>
> Hello,
>
> On 13/05/2019 22:35, Jacob Kroon wrote:
> > Hi Vladimir,
> >
> > On Mon, May 13, 2019 at 10:11 PM Vladimir 'phcoder' Serbinenko
> > <address@hidden> wrote:
> >>
> >> Ideally the option shouldn't be specific to GPT as other partmaps also 
> >> have stable IDs. I think it's better not to have short option at all
> >>
> >
> > Ok, I have some questions below.
> >
> >> On Mon, 13 May 2019, 20:33 Jacob Kroon, <address@hidden> wrote:
> >>>
> >>> Linux supports root=PARTUUID=<partuuid> boot argument, so add
> >>> support for probing it. Compared to the fs UUID, the partition
> >>> UUID does not change when reformatting a partition.
> >>>
> >>> Signed-off-by: Jacob Kroon <address@hidden>
> >>> ---
> >>>  docs/grub.texi             |  2 +-
> >>>  grub-core/commands/probe.c | 34 ++++++++++++++++++++++++++++++++++
> >>>  2 files changed, 35 insertions(+), 1 deletion(-)
> >>>
> >>> Changes since v4:
> >>>  * Do endianess byte-swapping on the fly when formatting string
> >>>
> >>> diff --git a/docs/grub.texi b/docs/grub.texi
> >>> index 308b25074..d85818744 100644
> >>> --- a/docs/grub.texi
> >>> +++ b/docs/grub.texi
> >>> @@ -4771,7 +4771,7 @@ a rest.
> >>>  @node probe
> >>>  @subsection probe
> >>>
> >>> address@hidden Command probe address@hidden var] 
> >>> @option{--driver}|@option{--partmap}|@option{--fs}|@option{--fs-uuid}|@option{--label}
> >>>  device
> >>> address@hidden Command probe address@hidden var] 
> >>> @option{--driver}|@option{--partmap}|@option{--fs}|@option{--fs-uuid}|@option{--label}|@option{--part-uuid}
> >>>  device
> >>>  Retrieve device information. If option @option{--set} is given, assign 
> >>> result
> >>>  to variable @var{var}, otherwise print information on the screen.
> >>>  @end deffn
> >>> diff --git a/grub-core/commands/probe.c b/grub-core/commands/probe.c
> >>> index 95d272287..b26cbe2cc 100644
> >>> --- a/grub-core/commands/probe.c
> >>> +++ b/grub-core/commands/probe.c
> >>> @@ -24,6 +24,7 @@
> >>>  #include <grub/device.h>
> >>>  #include <grub/disk.h>
> >>>  #include <grub/partition.h>
> >>> +#include <grub/gpt_partition.h>
> >>>  #include <grub/net.h>
> >>>  #include <grub/fs.h>
> >>>  #include <grub/file.h>
> >>> @@ -45,6 +46,7 @@ static const struct grub_arg_option options[] =
> >>>      {"fs",             'f', 0, N_("Determine filesystem type."), 0, 0},
> >>>      {"fs-uuid",                'u', 0, N_("Determine filesystem UUID."), 
> >>> 0, 0},
> >>>      {"label",          'l', 0, N_("Determine filesystem label."), 0, 0},
> >>> +    {"part-uuid",      'g', 0, N_("Determine GPT partition UUID."), 0, 
> >>> 0},
> >
> > Is "part-uuid" ok ? I guess I should remove "GPT" from the help text ?
>
> If I may interfere, lsblk names it PARTUUID (actually the case doesn't matter)
> so I'd suggest partuuidn withjout a hyphen.
>

I opted for "--part-uuid" since there already is "--fs-uuid", but I
don't have a strong opinion on the matter.

> And yes, this field exists also with a 'dos' partition label (or 'msdos"
> as parted calls it), not only a 'gpt'.
>
> I can't say for other partition labels than those two, having only
> used these.
>
>
> > I've seen both 0 and -1 being passed as short option, do they both
> > mean "no short option", or is there a preference which to use in this
> > case ?
> >
> > /Jacob
>
> Best,
>
> Didier