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I have to define a partitions layout for a embedded linux project. I have a board very similar to BeagleBoneBlack.

Project requires 5 partitions, so I have to use extended partition.

Question: Which extended partition type to use?

Two most commonly used are:

  • 0f W95 Ext'd (LBA) and
  • 05 extended

What is the difference?

0f is used by default when formatting in gparted (ubuntu). (It is windows 95 partition type.) 05 is used by default when formating by parted (ubuntu) or fdisk (linux board). (It is dos partition type.)

There is also 0x85 (linux extended), but even fdisk can not handle it.

Can someone please explain me what is the difference and limitations of this different types of extended partitions and what is recommended for embedded linux board?

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Given your use-case, if your board can boot it, I’d recommend using GPT instead of MBR. In fdisk, the g command will create a new GPT disklabel and you’ll be able to create all your partitions without worrying about extended partitions.

Now, to address your actual question, there is no practical difference under Linux. Partition type 5 is the historical, cylinder/head/sector-based extended partition type, which is theoretically limited to 8.4GB. Partition type F was introduced with Windows 95 to indicate LBA-based access, which isn’t limited to 8.4GB. There are various compatibility issues between DOS, Windows 95, 98 etc. and early versions of Windows NT, but that’s largely irrelevant now. See Andries E. Brouwer’s list of partition types for details (unfortunately, most of the links given there are now broken; the Internet Archive has some of them).

Linux only uses sector-based partition information, so even type 5 extended partitions aren’t limited. This can produce “amusing” layouts if you use DOS compatibility mode with fdisk — it will happily create an extended partition larger than 8.4GB with CHS information limiting it to 8.4GB...

Partition type 85 is also usable, but fdisk has a slight issue with it. If you create an extended partition and change its type to 85, fdisk will refuse to use it immediately, but if you write the resulting partition table and restart fdisk, it will happily create logical partitions inside the type 85 extended partition.

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