China DOS Union

The description in grub says that it can boot from the logical drive of the extended partition, such as (HD0,6) which is the seventh partition of the first hard disk, but it didn't work when I tried (using MAP). The first logical drive of the extended partition can work. Is it that it can only boot from the primary partition (including the first disk of the extended partition)?

I've never used Grub for DOS before, but it looks awkward, like Linux style.

Thanks for the bug report. Although I can't be sure this is really a bug.

You can search in a search engine for the article "------------------ GRUB FOR DOS Disk Emulation Command Introduction -----------------------" which has a more detailed description of hard disk emulation. If you can be sure it's not your operation error, then it can be confirmed as a bug.

You can post detailed operation steps, error messages, or other information you think is useful to help locate and solve the bug. It would be most helpful if you can (for example, using debug assembly language) post your primary partition table and all extended partition tables. In fact, without this partition table information, even if it is confirmed that such a bug exists, it may be difficult to solve. Thank you again for providing the report.

In Virtual PC, the main partition C and the extended partition have three partitions D, E, F. Is the description like this? (C-(hd0,0), D-(hd0,1), E-(hd0,2), F-(hd0,3)). Both D and E were formatted with FORMAT /S to build DOS systems. To boot from a non-first drive in the extended partition, MAP must be used. Trying to boot from E: map --read-only (hd0,2)+1 (hd0) gives an error message: no such partition. Booting from D is successful.

You seem to have not understood the corresponding relationship and differences between GRUB's partition representation and DOS/WINDOWS's partition representation. It is suggested that you first read the GRUB introductory materials before using GRUB. Judging from the phenomenon you described, this is not a bug of GRUB for DOS. But anyway, thank you for reporting the problem and thank you for paying attention to and using GRUB. I hope you will continue to support it.

Searching "GRUB introduction" in a search engine should be able to find some useful materials.

Successfully booted the hard disk partitions and floppy disk using GRUB FOR DOS, but always failed to boot the CD-ROM. When using the command line, "scdrom --install" reported an error saying "Invalid system partition" and "scdrom --bootcd" had the same error. "root (cd)" was invalid, and there was no chance to load chainloader /boot/grub/cdboot.bs. I don't know why.

The problem of GRUB booting from the CD - ROM is solved. I used to use WENGIER's GRUB FOR DOS, and there was an error when I typed commands to boot from the CD - ROM. Later, I downloaded CLIMBING's Chinese GRUB4DOS, and it was solved. It feels quite cool. Thanks...

But when using MAP to boot to DOS, there are many confusions in the logical partitions. I don't know if it is related to my previous partition modifications?

After MAP boots to DOS, there will be a strange phenomenon that the same partition is repeatedly assigned many drive letters..

Congratulations on solving the several problems you encountered.

The issue of drive letter confusion caused by map is sometimes normal. For example, if you map the first logical partition on the second hard disk as C:, then the second hard disk itself is still recognizable by BIOS, so DOS can also recognize it. In this way, you not only have the C: drive (which is the first logical partition of the original second hard disk), but also have drives like D: and E: (which are all partitions on the entire second hard disk. Obviously, C: is one of them). Such duplication is normal.

The usage of map for partitions seems that I haven't heard anyone say they have used it before, and you seem to be the first one. This usage is not used by many people, so the possibility of bugs is relatively high. I just tested it successfully on my own machine, but haven't tested it on more machines. I hope there are no serious problems. Thank you for using and reporting.

Thanks to Budian for the detailed introduction.