re: Need for a unique Linux GPT GUID type code (PATCH included)

[Rod Smith]

jdd wrote:

> Le 23/06/2011 06:38, Rod Smith a écrit :
>
>
>     At the risk of jumping the gun, I'm attaching a patch to implement my
>     suggestion in libparted.
>
> did you test it with windows? Because in non GPT disk, Windows never acknoledge 
> Linux drives, but always ask for formatting.
>
> I have no GPT disk to try

Yes, that's the whole point. In Windows, using the same GUID type code 
for Linux partitions that Windows uses for NTFS and FAT results in Linux 
partitions appearing in the list of available disks. Using a unique type 
code for Linux partitions, however, hides those partitions from Windows. 
This is desirable because it's easy to accidentally trash a Linux 
partition in Windows by double-clicking it. (Windows DOES ask before 
formatting it, but a user who's confused, tired, distracted, etc., could 
easily make the wrong choice.) If you've got a lot of Linux partitions, 
they also just clutter up the list of available Windows devices.

With MBR disks, this problem doesn't occur, because Linux has its own 
unique partition type code (0x83), and Windows doesn't try to access 
partition types it doesn't understand. Thus, on MBR disks, Linux 
partitions don't normally appear in the Windows list of disks (in the 
"Computer" window, among other places). Using a unique GUID type code 
for Linux makes GPT disks work like MBR disks in this respect.

You can test this with a USB flash drive: Put a GPT disklabel on it, 
create a Linux partition with the standard version of parted, create any 
Linux filesystem on it (I've tried ext2/3/4, ReiserFS, XFS, JFS, and 
BtrFS), and move it over to a Windows box. It'll pop up a dialog box 
asking if you want to format the disk. Do the same thing with my patched 
version of parted and it won't do that; Windows know enough not to try 
to access a partition that's marked with a type code it doesn't 
understand. The "Format..." option is also grayed out in Disk Management 
when you use a non-Windows partition type code GUID.

--
Rod Smith
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http://www.rodsbooks.com