what precisely is partition_entry_lba?

what precisely is partition_entry_lba?

[Benno Schulenberg]

Hi,

In libfdisk/src/gpt.c the function gpt_list_disklabel() prints
a GPT header, and one of the things it prints says:

_("Partitions entries LBA: %ju"), h->partition_entry_lba

In the struct this variable is described as:

uint64_t    partition_entry_lba; /* stat LBA of the partition entry array */

This doesn't make sense to me.  Shouldn't this say something
like "Starting block of the array of partition entries" instead?

All this use of 'lba' is confusing to me, as it stands for
"logical block addressing", and what seems to be meant
is simply "logical block" or "logical block number".  No?

Benno

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Re: what precisely is partition_entry_lba?

[Karel Zak]

On Mon, Sep 22, 2014 at 09:44:05PM +0200, Benno Schulenberg wrote:
> 
> Hi,
> 
> In libfdisk/src/gpt.c the function gpt_list_disklabel() prints
> a GPT header, and one of the things it prints says:
> 
> _("Partitions entries LBA: %ju"), h->partition_entry_lba
> 
> In the struct this variable is described as:
> 
> uint64_t    partition_entry_lba; /* stat LBA of the partition entry array */
> 
> This doesn't make sense to me.  Shouldn't this say something
> like "Starting block of the array of partition entries" instead?

EFI standard:

"The start of the GPT Partition Entry Array is located at the LBA
 indicated by the Partition Entry LBA field."

> All this use of 'lba' is confusing to me, as it stands for
> "logical block addressing", and what seems to be meant
> is simply "logical block" or "logical block number".  No?

Well, "LBA" is usually used as unit (especially in storage slang).
Don't think about it as about abbreviation :-)


IMHO the fdisk message "Partitions entries LBA: %ju" is fine, it's
better to follow commonly terminology.

    Karel


-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com

Re: what precisely is partition_entry_lba?

[Benno Schulenberg]

On Wed, Oct 1, 2014, at 09:59, Karel Zak wrote:
> On Mon, Sep 22, 2014 at 09:44:05PM +0200, Benno Schulenberg wrote:
> > uint64_t    partition_entry_lba; /* stat LBA of the partition entry array */
> > 
> > This doesn't make sense to me.  Shouldn't this say something
> > like "Starting block of the array of partition entries" instead?
> 
> EFI standard:
> 
> "The start of the GPT Partition Entry Array is located at the LBA
>  indicated by the Partition Entry LBA field."

Okay.  Then at least the relevant comment needs to be typo-fixed.
(Upcoming patch will do also that.)

> > All this use of 'lba' is confusing to me, as it stands for
> > "logical block addressing", and what seems to be meant
> > is simply "logical block" or "logical block number".  No?
> 
> Well, "LBA" is usually used as unit (especially in storage slang).
> Don't think about it as about abbreviation :-)

I can't -- my brain always auto-expands abbrevs.  :)

Well, I will just have to expand it as "Logical Block Address",
even though the word "Address" is completely superfluous.

> IMHO the fdisk message "Partitions entries LBA: %ju" is fine,

Not quite.  It would have to be either "Partitions entry" (where
one entry contains several paritions) or "Partition entries), where
each entry contains one partition, which is of course the case);
"Partitions entries" is nonsense in English.  Upcoming patch
makes the correction.

Benno

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