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Re: Unbootable machine



H. Peter Anvin wrote:
> Bernie Innocenti wrote:
>> On 06/02/09 03:43, H. Peter Anvin wrote:
>>> Bernie Innocenti wrote:
>>>> Disk /dev/sdb: 2055 MB, 2055208960 bytes
>>>> 221 heads, 2 sectors/track, 9081 cylinders
>>> I don't know where fdisk, the Linux kernel, or whatever come up with
>>> these kinds of geometries.  They're almost universally non-bootable.
>> Ok, I wiped mbr and made fdisk create a new one:
>>
>> Disk /dev/sdb: 2055 MB, 2055208960 bytes
>> 64 heads, 62 sectors/track, 1011 cylinders
>   ^^^^^^^^^^^^^^^^^^^^^^^^^^
> 
> Equally weird.  The only "standard" ones are 64 heads, 32 sectors and
> 255 heads, 63 sectors.

Depends on your definition of "standard".  Anything with {1 <= heads <= 255,
1 <= sectors <= 63, 1 <= cylinders <= 1023} meets the requirements of many
BIOS that I have encountered.  In particular, I have seen sectors/track of
2, 4, 28, 31, 32, 33, 47, 48, 60, 61, 62, 63, 128, 255 on booting drives
within the last two years.  Picking one of my USB 2.0 flash drives, I find
a Fujifilm 256 MB instance with
    128 heads, 4 sectors/track, 975 cylinders

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