[DriveSetup] add a "FixMBR" command

[starsseed]

When a disk already contains an Intel partition table, you can't write the boot code in the MBR (except to play with "dd" and a 'good' MBR)

As a workaround, you must :
-clean the MBR with DiskProbe ( write zeros to replace all the MBR content, especially the last 2 bytes).
-reboot
-create the partition table, create and format the partition.

Since USB flash drives rarely have a working MBR boot code, the installation is very difficult for unexperienced users.

​http://www.haiku-os.org/community/forum/bootable_usb

It's also a problem if you have multiple partitions on your disk.

Then DriveSetup need a command "FixMBR" to write the boot code.

[mmadia]

#5595 "implement cli application : writembr" is somewhat related.

[siarzhuk]

Going to publish this as GCI 2013 task.

[siarzhuk]

It looks like too hot for GCI teens. Sorry. :-\

[nephele]

I think this was fixed with ​https://git.haiku-os.org/haiku/commit/?id=1a7322a09e825d2445ca88a47cd1d5cd06d3811b ?

[pulkomandy]

This is about adding the same functionality in the UI of DriveSetup. Currently writembr is only a command line tool. DriveSetup writes the boot code only when creating a new partition table, but it never modifies existing boot code.

The description of the ticket explains very well what the problem is and this is still the case today.

[n0toose]

Can we invoke the CLI tool directly or should we rather try copying excerpts of the source code and adjust it for DriveSetup?

[pulkomandy]

All the needed code should already be available in DriveSetup since it is able to create a partition table with an MBR in it already. This only needs a "change only the bootcode and don't touch the partition table" codepath.