On Thu, May 16, 2019 at 02:18:51PM +0200, Thomas Schmitt wrote: > Hi, > > i quoted mformat.c: > > > /* install fake partition table pointing to itself */ > > Daniel Kiper wrote: > > OK, but why it is also done for FDD images? > > According to its man page, mformat formats floppies. So the question > would be why it creates a partition table at all.
Yeah, could you ask mformat folks about that? > > > Either mformat's result is ok or it is not. > > > I would say that in most cases it works but is some it does not. This > > is difficult to say right now where is the bug > > Whoever is the culprit when stepping into a pitfall, grub-mkrescue should > try to avoid known bug triggers. Yep but on the other hand we have to not break anything which works right now. > I understand from Vladimir's reply that he did not think of partition > tables or floppies when employing mformat in grub-mkrescue.c. He wanted > a FAT filesystem with usual entrails. > Usual is to have no data in it which look like a partition table entry > which describes a partition starting at block 0. > (Microsoft hasn't. The larger Linux distros haven't.) > > So i propose the change as fine tuning of the original developer's > intention. (Vladimir will correct me if i'm wrong.) After some thinking I have an itching to add the "-k" option to the mformat. However, I am not convinced that this should go into the release. There is a chance that we will break other platforms and fix the only one. So, I would suggest to make this as a known issue and fix it after the release. Does it make sense? > > So, first of all I would like to understand why somebody decided to do that > > As for the Macbook, my theory is that it tries to explore what it believes > to be an extended partition. Newer Macbooks are said not to make this > mistake any more. > > As for mtools, binary search on > http://svn.savannah.gnu.org/viewvc/mtools/trunk/mformat.c?view=log > yields that the comment came in with revision 4 in line 958 > > http://svn.savannah.gnu.org/viewvc/mtools/trunk/mformat.c?revision=4&view=markup > Revision 2, line 800 shows no trace of a partition table until in the > end 0xaa55 is written. > Revision 4 is from 2002 and has as commit message "3.9.8, modified files". > > Committer is "aknaf", probably the same as "alainknaff" who committed > to mtools last year. > https://savannah.gnu.org/users/alainknaff > Maybe he still can remember why he added the partition entry. Could you ask him about that? Please keep grub-devel in the loop. > -------------------------------------------------------------------------- > > > > After all it is quite easy to override the ideas of grub-mkrescue > > > before the ISO gets packed up. In practice, it's preference for GPT > > > makes more problems than its preference for mformat. > > > This is not good idea. I would like to see a fix or at least a kind of > > workaround in GRUB upstream. > > I was not happy with Vladimir's decision to use GPT instead of MBR partition > table. (Because of non-mountable partitions and the GPT backup, which needs > to be relocated after copying the ISO onto USB stick.) I am not sure I understand. Which GPT do you refer to? Daniel _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
