GNU bug report logs - #19135
mklabel gpt always creates 128 partition entries

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: "Ulrich Windl" <Ulrich.Windl <at> rz.uni-regensburg.de>
To: <bug-parted <at> gnu.org>
Subject: mklabel gpt always creates 128 partition entries
Date: Fri, 21 Nov 2014 08:33:43 +0100

This is halfway a bug and halfway an enhancement:

parted's "mkpart gpt" always creates a Partition Entry Array with 128 entries.
It may be due to misunderstanding the UEFI docs that state the size of the partition entry should be a multiple of 128.
At the moment the Partition Entry Table needs 16kB (128*128). That's no much, especially when considering that most systems align data structures to 1MB boundaries.
An argument against it would be that at least 90% of all disks have less than 5 partitions, and I guess 99% have less than 10 partitions on the disk, so 128 seems to be an overkill. Even if unused, a program has to read and check all these unused entries.

(I created a GPT label on a 3MB test image)

Part of the enhancement is: Supply an additional parameter to "mklabel gpt" that allows to specify the size (number of entries) in the GPT Partition Entry Table, or even provide a command to resize it.

Message #8 received at 19135 <at> debbugs.gnu.org (full text, mbox):

From: Håkon Løvdal <hlovdal <at> gmail.com>
To: Ulrich Windl <Ulrich.Windl <at> rz.uni-regensburg.de>
Cc: 19135 <at> debbugs.gnu.org
Subject: Re: bug#19135: mklabel gpt always creates 128 partition entries
Date: Fri, 21 Nov 2014 17:06:49 +0100

On 21 November 2014 08:33, Ulrich Windl
<Ulrich.Windl <at> rz.uni-regensburg.de> wrote:
> parted's "mkpart gpt" always creates a Partition Entry Array with 128 entries.

Is this also observed with version 2.3 of parted? If so can you
reproduce with the latest version, 3.2?

BR Håkon Løvdal

Message #11 received at 19135 <at> debbugs.gnu.org (full text, mbox):

From: "Ulrich Windl" <Ulrich.Windl <at> rz.uni-regensburg.de>
To: <19135 <at> debbugs.gnu.org>
Subject: Antw: bug#19135: Acknowledgement (mklabel gpt always creates
 128 partition entries)
Date: Mon, 24 Nov 2014 08:04:50 +0100

It turned out that UEFI spec 2.4 states the Partition Entry Array should be at least 16kB (which is nonsense, because they should better define the number of entries) which gives 128 Entries.
However why have all those flexible data structures if the number of Pertition Entries is fixed?
I still believe 128 Pertition Entries is severe overkill.

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