Liam Proven composed on 2024-03-04 19:17 (UTC):
> tsiegel wrote:
>> There should be only one active primary partition at any given time.
> Picky-picky. OK, then, reorder the adjectives so that it is no longer
> grammatical English but is more technically accurate.
> The active, first primary partition.
> Or, in other words, in the first primary partition, which should be active.
This explanation is also ambiguous. It /may/ have been that prior to DOS 3.3,
DOS
4 or DOS 5 that the boot flag needed to be on the /first/ partition (also
primary), but at some point by DOS 5 (same time frame as OS/2's Boot Manager?;
v1.3?) it became the rule that DOS will boot directly via legacy/DOS/Windows MBR
code, as long as one, and only one, primary partition is marked active. It will
boot if: 1-that first/only active primary partition is any of first, second,
third
or fourth partition in physical or logical order on the disk or in the partition
table; and 2-the disk is small enough that the active primary is addressable by
DOS. IOW, DOS can boot from *any* primary on the first BIOS disk, as long as
that
primary is the /only active/ primary.
Here are two example valid layouts, which are both in current use, and have been
in use since before the birth of SATA:
# parted -l
Model: ATA ADATA SU800 (scsi)
Disk /dev/sda: 256GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags:
Number Start End Size Type File system Flags
1 32.3kB 107MB 107MB primary hidden, type=17 (OS/2)
2 107MB 115MB 8225kB primary boot, type=0a (IBM BM)
3 115MB 378MB 263MB primary fat16 type=06 (PC DOS 2000)
4 378MB 183GB 182GB extended type=05
5 378MB 387MB 8193kB logical hidden, type=11
6 387MB 650MB 263MB logical fat16 type=06
7 658MB 872MB 214MB logical ext2 type=83
8 872MB 1135MB 263MB logical fat16 hidden, type=16
9 1818MB 9369MB 7551MB logical ext3 type=83
10 9377MB 10.2GB 839MB logical type=07
11 10.4GB 12.5GB 2097MB logical type=07
12 12.9GB 13.9GB 979MB logical type=07
13 13.9GB 16.5GB 2624MB logical type=07
14 16.5GB 22.4GB 5873MB logical ext3 type=83
15 22.4GB 25.3GB 2887MB logical ext3 type=83
16 25.3GB 32.9GB 7551MB logical ext4 type=83
17 32.9GB 40.2GB 7345MB logical ext3 type=83
...
# parted -l
Model: ATA ST3160215ACE (scsi)
Disk /dev/sda: 160GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Number Start End Size Type File system Flags
1 32.3kB 214MB 214MB primary ext2 boot, type=83
2 214MB 222MB 8225kB primary ext2 type=83
3 222MB 263MB 41.1MB primary fat16 type=06
4 263MB 144GB 144GB extended type=05
5 263MB 1341MB 1077MB logical linux-swap(v1) type=82
6 1341MB 6375MB 5034MB logical ext3 type=83
...
Note the boot flags are currently on the non-DOS #1 or #2 primary, but the IBM
DOS
installed on partition 3s do boot directly via compatible MBR code when the flag
is moved to partition 3 from partition 1 or 2.
> (I have had success when it's the first partition, which is also a
> primary partition, but a different partition is active: e.g. DOS or
> Win9x is in partition 1, but Linux is in partition 2, that's active,
> and Linux's GRUB passes control to the 1st partition.)
That works here too, but without necessity for the sole boot flagged DOS
partition
to be the first partition physically or logically. When Grub chainloads DOS, the
point in time for relevance of boot flag to boot process has already expired.
Actually, when Grub code has replaced DOS/OS2/Windows-compatible boot code in
MBR,
the boot flag plays no part in boot process at all, had no beginning to expire.
:)
--
Evolution as taught in public schools is, like religion,
based on faith, not based on science.
Team OS/2 ** Reg. Linux User #211409 ** a11y rocks!
Felix Miata
_______________________________________________
Freedos-user mailing list
Freedos-user@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/freedos-user
