# Extended DOS logical partitions not populated in /dev



## Nezmer (Mar 24, 2010)

Hi,

If I understand correctly, FreeBSD supports Extended DOS partitions/slices. Unfortunately, The logical volumes under such a slice(ad6s4) never showed up in my system (8.0 then 8/stable amd64).

Do I need to do something special to make this work?


```
# fdisk
******* Working on device /dev/ad6 *******
parameters extracted from in-core disklabel are:
cylinders=969021 heads=16 sectors/track=63 (1008 blks/cyl)

Figures below won't work with BIOS for partitions not in cyl 1
parameters to be used for BIOS calculations are:
cylinders=969021 heads=16 sectors/track=63 (1008 blks/cyl)

Media sector size is 512
Warning: BIOS sector numbering starts with sector 1
Information from DOS bootblock is:
The data for partition 1 is:
sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
    start 63, size 96389937 (47065 Meg), flag 0
        beg: cyl 0/ head 1/ sector 1;
        end: cyl 1023/ head 15/ sector 63
The data for partition 2 is:
<UNUSED>
The data for partition 3 is:
sysid 165 (0xa5),(FreeBSD/NetBSD/386BSD)
    start 96390000, size 57207024 (27933 Meg), flag 80 (active)
        beg: cyl 1023/ head 255/ sector 63;
        end: cyl 1023/ head 15/ sector 63
The data for partition 4 is:
sysid 5 (0x05),(Extended DOS)
    start 153597465, size 823170600 (401938 Meg), flag 0
        beg: cyl 1023/ head 255/ sector 63;
        end: cyl 1023/ head 14/ sector 63
```



```
% ls -l /dev/ad6*
crw-r-----  1 root  operator    0,  88 Mar 24 13:34 /dev/ad6
crw-r-----  1 root  operator    0,  89 Mar 24 13:34 /dev/ad6s1
crw-r-----  1 root  operator    0,  90 Mar 24 13:34 /dev/ad6s3
crw-r-----  1 root  operator    0,  92 Mar 24 13:28 /dev/ad6s3a
crw-r-----  1 root  operator    0,  93 Mar 24 13:34 /dev/ad6s3b
crw-r-----  1 root  operator    0,  91 Mar 24 13:34 /dev/ad6s4
```


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## jb_fvwm2 (Mar 25, 2010)

```
mkdir /ext_dos1
mkdir /ext_dos2
mount_msdosfs /dev/ad6s5 /ext_dos1
mount_msdosfs /dev/ad6s6 /ext_dos2
```
Probably would work, I'm guessing.
............
Another guess you can probably just ignore:
since ad6s3 etc already are listed...
............
If those fail, do you have geom_bsd.ko 
geom_label.ko and geom_mbr.ko loaded?


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## fbsd1 (Mar 25, 2010)

Look close at fdisk listing. It says there are 16 heads. Slice 1 starts at the begining of the disk .

```
beg: cyl 0/ head 1/ sector 1;
end: cyl 1023/ head 15/ sector 63
```

But its not marked as active. That means you are not booting from that slice.


```
Slice 3
beg: cyl 1023/ head 255/ sector 63;
end: cyl 1023/ head 15/ sector 63

Slice 4
beg: cyl 1023/ head 255/ sector 63;
end: cyl 1023/ head 14/ sector 63
```

Something is wrong here. Both slice 3 & 4 start at the same location on disk (cyl 1023).
And they are using 255 heads when the Hard drive only has 16 heads.
I donâ€™t think its Freebsd problem but problem with how you created the dos partitions on the HD to begin with.


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## jalla (Mar 25, 2010)

fbsd1 said:
			
		

> Look close at fdisk listing. It says there are 16 heads. Slice 1 starts at the begining of the disk .
> beg: cyl 0/ head 1/ sector 1;
> end: cyl 1023/ head 15/ sector 63
> 
> ...



The reporting of cyl/head/sector in fdisk has always been whacky for disks with more than 1024 logical cylinders. Just ignore it. Look at the values of start and size instead, they should be correct.

WRT the active slice I don't think freebsd cares, it will boot off any slice whether it's active or not.


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## Nezmer (Mar 25, 2010)

jb_fvwm2 said:
			
		

> ```
> geom_mbr.ko[/quote]
> 
> bingo
> ```


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