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Bug confirmed (Users)

posted by RayeR Homepage, CZ, 16.01.2021, 05:14
(edited by RayeR on 16.01.2021, 05:57)

Would't you try to compare the partition creation using MS-DOS 6.2x FDISK (on smaller partition) if it lead to same problem?

BI Type                    Start-C/H/S   End-C/H/S     Sector     Size     MB  abs. Start/End
----------------------------------------------------------------------------------------------
80 0e Prim. DOS,FAT16,LBA     0/  1/ 1  975/ 63/32         32    4096000  2000 32-4096031
00 0c Prim. DOS,FAT32,LBA   976/  0/ 1  534/ 63/32    4096000  120731648 58951

Well I see the problem here. It's tricky that cylinder value already overflows 10bit storage in partition entry. One simple approach would be to start next partition just by incrementing the cylinder of previous end value (975+1)&0x3FF=976. Other approach would be to calculate CHS from LBA value. Last LBA is 4096031 so next partition should start at LBA 4096032 or further. If one do simple calculation like 4096032/64/32=2000.015625 and truncate it to 2000 then & 3FF = 976 and things goes wrong. It should check the reminder and round up to 2001 then & 3FF = 977. Back to LBA it would give 4098048 so ~1MB wasted gap but better than overlap.

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DOS gives me freedom to unlimited HW access.

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