a.verardo at tecmav.fastwebnet.it
Tue Mar 9 16:34:34 UTC 2004
Victor V. Vengerov wrote:
> 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.
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 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
>> 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 ?
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