Vim Visual wrote:
>
> Ok... first question...
>
> Before I ask it, I would like to say that I printed out the
> installation guide for 4.0 and did read it *in detail*
>
> So, as I told you I had an ubuntu system on the laptop (I am using now
> an ibm t43p to test OpenBSD before I install it on the laptop I use as
> a production machine)
>
> The installation guide gives a nice example of a system with a windows
> partition on it.
>
> I intend to enable in the future the suspend-to-disk option and I see
> that ubuntu had done a partition in the end of the disk with a size of
> ~4GB, so that I presume this is the partition for this feature.
> Therefore I do not delete it and let it as it is. Then I proceed with
> the fdisk step and edit the zero partition, which has a size of 73GB
> or so: e 0
>
> My problem is that I don't understand what this paragraph means:
>
> "On platforms which use fdisk, it is important that the first
> partition skips the first track of the disk, in this case, starting on
> sector 63. This will vary from machine to machine and disk system to
> disk system. If an OpenBSD partition is created starting at offset 0,
> this partition table will end up being overwritten by the OpenBSD
> partition's Partition Boot Record."
CHS is one way of addressing stuff on a disk drive.
Disks actually used to be accessed this way.
C Cylenders refer to where the seek arm is positioned.
Cylenders run from 0 thru some maximum.
Some things access only the low bits (modulo 1024) of the cylinder number.
H Heads refer to which read/write head is electronically selected.
Heads run from 0 thru some maximum (originally how many platters)
S Sectors run from 1 thru some number, generally 63 on modern drives.
(There really is a sector 0. Do not mess with it.
--- low level formatting which probably requires a bunch of stuff you do not
have)
fdisk should show something like:
# fdisk wd0
Disk: wd0 geometry: 4866/255/63 [78172290 Sectors]
Offset: 0 Signature: 0xAA55
Starting Ending LBA Info:
#: id C H S - C H S [ start: size ]
------------------------------------------------------------------------
0: 00 0 0 0 - 0 0 0 [ 0: 0 ] unused
1: 00 0 0 0 - 0 0 0 [ 0: 0 ] unused
2: 00 0 0 0 - 0 0 0 [ 0: 0 ] unused
*3: A6 0 1 1 - 4865 254 63 [ 63: 78172227 ] OpenBSD
Note that the partition starts on HEAD 1
(whereas the cylinder really starts with head 0)
Note that the LBA starts with 63
(unless you have a very stange disk, it will look very similar)
Note that the disk lies about its geometry
(so that more can be crammed into the first 1024 cylinders)
It may help to realize that OpenBSD works on hardware
that is VERY different from Microsoft DOS. Disks included.
OpenBSD can have disk drives that DO NOT HAVE PARTITION TABLES.
Main reason for Partition Table is to not confuse Linux and Windows
(and BIOS which you probably need for booting)
To further complicate matters OpenBSD uses what it calls a disklabel
# disklabel wd0
# Inside MBR partition 3: type A6 start 63 size 78172227
--- The "inside" note is kinda nice, but probably irrelevant except for ...
16 partitions:
# size offset fstype [fsize bsize cpg]
a: 307377 63 4.2BSD 2048 16384 304 # Cyl 0*-
304
b: 716688 307440 swap # Cyl 305 -
1015
c: 78177792 0 unused 0 0 # Cyl 0 -
77557*
d: 2048256 1024128 4.2BSD 2048 16384 328 # Cyl 1016 -
3047
e: 1024128 3072384 4.2BSD 2048 16384 328 # Cyl 3048 -
4063
f: 1024128 4096512 4.2BSD 2048 16384 328 # Cyl 4064 -
5079
g: 1024128 5120640 4.2BSD 2048 16384 328 # Cyl 5080 -
6095
h: 72027522 6144768 4.2BSD 2048 16384 328 # Cyl 6096 -
77551*
This is what actually matters to OpenBSD.
Of these, wd0c refers to the entire disk (NOT to the OpenBSD part of the
disk)
Probably, wd0a is / and wd0b is swap. Probably.
There is no reason that the OpenBSD (slices I think they're called)
have to be contiguous. Overlapping is probably a "bad idea".
>
> How many C/H/S are a track? I try to assign an offset to the first
> partition, I tried both with CHS and raw mode but in the end the same
> happens always: I go through the install, which is rather easy and
> logical, download the system, install it and halt to reboot afterwards
> and... alas, fortune and glas break soon: When the laptop is booting I
> get a GRUB message popping up and saying that it cannot load the
> system. Of course, this GRUB used to belong to ubuntu and it must be
> in the first track, somewhere... if I give an offset to the first
> partition, this residual ubuntu thing will be sill there...
>
> Of course, I can always go for the "use the whole disk for OpenBSD"
> but then that potential suspend-to-disk partition will be deleted. On
> the other hand, what I am interested on is NOT suspend to disk, but
> suspend to ram. But being prudent as I am, I am aware that this may
> not work out and I want to leave open the possibility of suspending to
> disk in case of.
>
> I guess I am doing something wrong, but what?
>
> I was a good boy, I read the documentation and this is not a
> MY-OPENBSD-DOES-NOT-BOOT-HELP! message... don't throw tomatoes to me,
> please...
>
> Cheers,
>
> Pau
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