Re: [Gptfdisk-general] sgdisk and Hybrid without prepend of EFI partition support

[Mario F. <mar...@gm...>]

i am in the process of creating a gentoo based distributin for Buffalo nas
devices from the version of MBR based u-boot to the new versions that only
support GPT partitions. beacuase of the "be cost effevtive" these devices
onyl support most of the times only mbr or gpt (small flash rom 512kb)
i dont want to stress on creating 2 different versions of the disk images
one for the old and one for the new devices
so i use the hybrid and it works great
let the first part appear as mbr and then linux will work on as gpt
and the gpt based also work
mbr is a woraround these old u-boot boot managers

for ex

GenLSPro ~ # sgdisk -p /dev/sda
Disk /dev/sda: 195371568 sectors, 93.2 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): 45311E30-AEFA-454F-9A1A-E5DC2632D0D0
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 195371534
Partitions will be aligned on 2048-sector boundaries
Total free space is 2014 sectors (1007.0 KiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048          616447   300.0 MiB   8300  Linux filesystem
   2          616448       168388607   80.0 GiB    8300  Linux filesystem
   3       168388608       170485759   1024.0 MiB  8200  Linux swap
   4       170485760       195371534   11.9 GiB    8300  Linux filesystem


GenLSPro ~ # fdisk /dev/sda
Welcome to fdisk (util-linux 2.22.1).

Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.


WARNING: GPT (GUID Partition Table) detected on '/dev/sda'! The util fdisk
doesn't support GPT. Use GNU Parted.


Command (m for help): p

Disk /dev/sda: 100.0 GB, 100030242816 bytes, 195371568 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048      616447      307200   83  Linux

Partition table entries are not in disk order

Command (m for help):

yes its a special case but would simplyfy my automatic image creatin process
now i am piping and its only working 2 of 3 times
r
h
1
n
83
y
n
w
y | gdisk /dev/sda


2012/11/21 Rod Smith <rod...@ro...>

> On 11/21/2012 06:45 AM, Mario Fetka wrote:
> > sgdisk when run with -h to create a Hybrid part/tables will always add
> > an EFI part bevore the specified partitons
> > a EFI part is not needed on arm devices
> >
> > could you plz add for ex
> >
> > -H, --hybrid-noefi=partnum[:partnum...]
> >                                create hybrid MBR without prepended EFI
>
> If I understand correctly, you're saying that you've got an ARM device
> that will recognize a GPT disk even without a 0xEE protective partition
> in the MBR. I've never before heard of an OS or utility that would
> interpret a disk as GPT even when it's lacking a 0xEE protective MBR
> partition. I'm reluctant to add support for creating such disks because
> so many other OSes and utilities will NOT interpret them as you might
> expect, so this will just end up creating more problems, beyond those
> that hybrid MBRs already create.
>
> If you can point me to more detailed documentation of what can actually
> use such an extreme configuration and why it might be helpful, I might
> reconsider this decision.
>
> --
> Rod Smith
> rod...@ro...
> http://www.rodsbooks.com
>
>
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