* On 5/20/19 6:52 PM, Thomas Schmitt wrote: > in the course of a problem search between GRUB, Guix, and xorriso we found > the trigger of a problem with some old Macbook EFI firmware in a gesture > of mformat. > Line 1375 of > > http://svn.savannah.gnu.org/viewvc/mtools/trunk/mformat.c?revision=506&view=markup > has > > /* install fake partition table pointing to itself */ > > Now we are wondering for which use case there is this MBR partition table > entry starting with LBA 0 and claiming the whole device. > > The SVN at savannah shows that this gesture was introduced with revision 4 > in may 2002 by "aknaff". My hope is that this was you and that you can tell > grub-devel (Cc'ed) more about the motivation.
No authoritative answer from me, but if this is coupling GPT + MBR, creating a MBR partition table from LBA 0 to the end of (reachable) device space (which is not necessarily the actual device space/end for limiting factors such as disk sector size [mis-]usage and the like) is a pretty common thing to do and called "protective MBR". The rationale being to "trick" tools that are only MBR-aware into thinking that the device is NOT unpartitioned and hence not erroring out or offering to "correct the situation". Mihai
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