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Re: disklabel support
From: |
tripun goel |
Subject: |
Re: disklabel support |
Date: |
Thu, 12 Apr 2012 20:23:32 +0530 |
On Thu, Apr 12, 2012 at 8:17 PM, Vladimir 'φ-coder/phcoder' Serbinenko
<address@hidden> wrote:
> On 12.04.2012 16:43, tripun goel wrote:
>> Please see if this helps ?
>> http://leaf.dragonflybsd.org/cgi/web-man?command=disklabel64§ion=8
> It doesn't. You need on-disk format.
>
72/*
73 * A disklabel64 starts at slice relative offset 0, NOT SECTOR 1. In
74 * otherwords, d_magic is at byte offset 512 within the slice, regardless
75 * of the sector size.
76 *
77 * The d_reserved0 area is not included in the crc and any kernel writeback
78 * of the label will not change the d_reserved area on-disk. It is purely
79 * a shim to allow us to avoid sector calculations when reading or
80 * writing the label. Since byte offsets are used in our 64 bit disklabel,
81 * the entire disklabel and the I/O required to access it becomes
82 * sector-agnostic.
83 */
84struct disklabel64 {
85 char d_reserved0[512]; /* reserved or unused */
86 u_int32_t d_magic; /* the magic number */
87 u_int32_t d_crc; /* crc32() d_magic thru last part */
88 u_int32_t d_align; /* partition alignment requirement */
89 u_int32_t d_npartitions; /* number of partitions */
90 struct uuid d_stor_uuid; /* unique uuid for label */
91
92 u_int64_t d_total_size; /* total size incl everything (bytes) */
93 u_int64_t d_bbase; /* boot area base offset (bytes) */
94 /* boot area is pbase - bbase */
95 u_int64_t d_pbase; /* first allocatable offset (bytes) */
96 u_int64_t d_pstop; /* last allocatable offset+1 (bytes) */
97 u_int64_t d_abase; /* location of backup copy if not 0 */
98
99 u_char d_packname[64];
100 u_char d_reserved[64];
101
102 /*
103 * Note: offsets are relative to the base of the slice, NOT to
104 * d_pbase. Unlike 32 bit disklabels the on-disk format for
105 * a 64 bit disklabel remains slice-relative.
106 *
107 * An uninitialized partition has a p_boffset and p_bsize of 0.
108 *
109 * If p_fstype is not supported for a live partition it is set
110 * to FS_OTHER. This is typically the case when the filesystem
111 * is identified by its uuid.
112 */
113 struct partition64 { /* the partition table */
114 u_int64_t p_boffset; /* slice relative offset, in bytes */
115 u_int64_t p_bsize; /* size of partition, in bytes */
116 u_int8_t p_fstype;
117 u_int8_t p_unused01; /* reserved, must be 0 */
118 u_int8_t p_unused02; /* reserved, must be 0 */
119 u_int8_t p_unused03; /* reserved, must be 0 */
120 u_int32_t p_unused04; /* reserved, must be 0 */
121 u_int32_t p_unused05; /* reserved, must be 0 */
122 u_int32_t p_unused06; /* reserved, must be 0 */
123 struct uuid p_type_uuid;/* mount type as UUID */
124 struct uuid p_stor_uuid;/* unique uuid for storage */
125 } d_partitions[MAXPARTITIONS64];/* actually may be more */
126};
> --
> Regards
> Vladimir 'φ-coder/phcoder' Serbinenko
>
>
>
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