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| alt.os.development | Operating system development chatter | 4,255 messages |
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| Message 4,103 of 4,255 |
| wolfgang kern to All |
| Re: Secrets on UEFI GPT |
| 09 Feb 24 15:31:13 |
From: nowhere@never.at because nobody responded to my questions and I couldn't find anything on the net it seems some parts of the story are intentional well hidden. So now I have to try and fail, which may cost me several month. And whenever/if at all I find these missing info I will keep it a secret as well. On 27/01/2024 09:50, I wrote: > my attempt to manually create a complete UEFI startup with KESYS hexwork > still encounter many obstacles :) > QUESTIONS still are: what should I enter into > 1. the 64 bit Disk GUID (also referred as UUID on UNIXes)? > 2. the 64 bit GUID for FAT32 start partition (first entry in LBA_2)? > 3. is it really required to waste 33 sectors for never used entries? >   or would my short (only one sector) solution work as well? > > please tell me what I may have missed and what's different to your > settings. > TIA > __ > wolfgang > >> what I have so far: >> (almost all is in hex, b/w/q/dq/qq mean 8/16/32/64/128 bit) > > corrected (was off by one): > LBA_0:         MBR > 0000...        all Zero > 01BE 01        BootIndicator >   Set to 0x00 to indicate a non-bootable partition. >   If set to any value the behavior of this flag on non-UEFI systems is > undefined. >   Must be ignored by UEFI implementations. > 01BF 00 02 00  StartingCHS ;means LBA_01 > 01C2 EE        OSType (i.e GPT Protective) > 01C3 FF FF FF  EndingCHS > 01C6 q 01      StartingLBA > 01CA q FFFFFFFF Size of whole disk (in sectors-1); less if smaller > 01CE ...       remaining Partition Records shall each be set to zeros. > 01FE 55 AA > ------------------ >> [LBA_1] GPT header >> 000 45 46 49 20 50 41 52 54 ;"EFI PART" Signature >> 008 00 00 01 00  Revision for GPT version 1.0 >>                   (through at least UEFI version 2.3.1), >> 00C 5C 00 00 00  Header size (in bytes) >> 010 q 0         CRC32 of header (offset +0 up to header size), >>                   with this field zeroed during calculation >> 014 q 0         Reserved; must be zero >> 018 dq ....      Current LBA (location of this header copy) >> 020 dq ....      Backup LBA (location of the other header copy) >> 028 dq 4         First usable LBA for partitions (primary last LBA + 1) >>     specs say minimum 6 for 4K sectors and 34dec for 512 byte sectors >>     what a waste ... >> 030 dq ....      Last usable LBA (secondary partition first LBA - 1) >> 038 dq ???       Disk GUID (also referred as UUID on UNIXes) >> 048 dq 2         Starting LBA of array of partition entries >>                   (always 2 in primary) >> 050 q 00000004  Number of partition entries in array >> 054 q 00000080  Size of a single partition entry (usually 128) >> 058 q 0         CRC32 of partition array >> 05C..end of sector; all ZERO >>      (420 bytes for 512 byte sectors; but more with larger sector sizes) >> --------------------------- >> [LBA_2] I'd have only four partition entries assigned >> GUID partition entry format [128 byte each] >> 000 qq         Partition type GUID >> 1.   ??? boot part                                   ;FAT32 >> 2.   "KESYS 64 ddmm2024" to be declared global unique ;KESYS64 >> 3.   28 73 C1 2A-1F F8 D2 11 BA 4B 00 A0 C9 3E C9 3B ;EFI >> 4.   16 E3 C9 E3 5C 0B B8 4D 81 7D F9 2D F0 02 15 AE ;M$ reserved >>       ???                                             ;or NTFS >> 010 qq ???    Unique partition GUID >> 020 dq 4/x/x/x First LBA (specs say 6 or 34 for first partition) >> 028 dq         Last LBA (inclusive, usually odd) >> 030 dq        Attribute flags >> 038 str       72 bytes Partition name (36 UTF-16LE code units) >> >> The 64-bit partition table attributes are shared between 48-bit common >> attributes for all partition types, and 16-bit type-specific attributes. >> |
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