DOSFS problems

[Adriano Verardo]

Hi, Victor.

Victor V. Vengerov wrote:

> Adriano,
>
> As fine as I understand you need proper MBR on your HDD to run
> dosfs test.

Yes, QUANTUM ELS 127A, CHS=919/16/17, DOS 6.22,
Install from scratch, 16 MB partition.
MBR:
00 - FA 33 C0 8E  D0 BC 00 7C 8B F4 50 07 50 1F FB FC
16 - BF 00 06  B9 00 01  F2 A5 EA  1D 06 00  00  BE  BE 07
32 - B3 04  80 3C  80 74  0E 80 3C 00  75 1C 83 C6 10 FE
48 -  CB 75 EF CD 18 8B 14 8B 4C 02 8B EE 83 C6 10 FE
64 -  CB 74 1A 80 3C 00 74 F4 BE 8B 06 AC 3C 00 74 0B
....
Unexpected 07 50 in MBR[11,12]. Should be 00 02 according with the disk
and DOSFS needs.

>
>
> As I remember, you may re-initialize MBR on your HDD invoking
>
> fdisk /mbr
> (or fdisk C: /mbr ?)

Done, no changes.

>
> Then, run fdisk C: and ensure that your partition table is correct.
> If problem persists, try to reduce partition size to, let say, 256Mb
> using fdisk. 

Tried 16 M ... unbelievable behaviour.
Thank you, pleased to hear from you.
Adriano

>
>
> Regards,
> Victor
>
> Adriano Verardo wrote:
>
>> Thomas Doerfler wrote:
>>
>>> Could you possible give the values that are present in your MBR and 
>>> partition table? It may be that the RTEMS DOSFS code does not 
>>> implement ALL possible partition types and options.
>>>
>> Hi Thomas, thank you again.
>>
>> The result of all tests is: the simplest possible DOS install always 
>> gives
>> working system disks with a MBR that's never accepted by DOSFS.
>> For all tested DOS/fdisk/HW/FAT type/ etc etc. combinations:
>> - HD MBR zeroed before installing DOS
>> - no disk managers, installed DOS boots from C: and works
>> - probably DOSFS fails before accessing the partition table:
>>  * MBR[11,12] of the HD is always wrong (huge, ie: 07 50 instead of 
>> 00 20
>>     and changes using different fdisk/format tools)
>>  * the final 55 AA signature on the HD MBR is sometimes absent (00 00)
>> - the initial OEM FIELD on the HD MBR is never an ASCII string ?????
>> - the partition tab is @ offset 446 ... standard ... DOS works
>> - the MBR of the install floppy seems always to be "regular"... why 
>> it is not
>>   reproduced (with the obvious changes) on the HD ???
>>
>> Forcing rigth values in the DOSFS source don't work.
>> Clearly there are other inconsistent values in the MBR.
>>
>> If this info are not precise enough I'll send some MBR dumps.
>> It's not immediate to transfer them to my PC.
>>
>> Is there any other rtems-user who had a similar problem ?
>> Using very standard but quite old HW can be a problem ?
>> Is there any particular DOS install procedure/trick/option to
>> force the layout of  the MBR of the HD ?
>>
>> Adriano
>>
>>
>>
>>
>>
>
>