Tribblix: manual page: efi_alloc_and

EFI_ALLOC_AND_INIT(3EXT) Extended Library Functions

NAME

efi_alloc_and_init, efi_alloc_and_read, efi_free, efi_write,
efi_use_whole_disk, efi_reserved_sectors - manipulate a disk's EFI
Partition Table

SYNOPSIS

cc [ flag ... ] file... -lefi [ library ... ]
#include <sys/vtoc.h>
#include <sys/efi_partition.h>

int efi_alloc_and_init(int fd, uint32_t nparts, dk_gpt_t **vtoc);

int efi_alloc_and_read(int fd, dk_gpt_t **vtoc);

void efi_free(dk_gpt_t *vtoc);

int efi_write(int fd, dk_gpt_t *vtoc);

int efi_use_whole_disk(int fd);

uint_t efi_reserved_sectors(dk_gpt_t *vtoc);

DESCRIPTION

The efi_alloc_and_init() function initializes the dk_gpt_t structure
specified by vtoc in preparation for a call to efi_write(). It
calculates and initializes the efi_version, efi_lbasize, efi_nparts,
efi_first_u_lba, efi_last_lba, and efi_last_u_lba members of this
structure. The caller can then set the efi_nparts member.

The efi_alloc_and_read() function allocates memory and returns the
partition table.

The efi_free() function frees the memory allocated by
efi_alloc_and_init() and efi_alloc_and_read().

The efi_write() function writes the EFI partition table and creates a
Protective Master Boot Record (PMBR); see below.

The efi_use_whole_disk() function takes any space that is not
contained in the disk label and adds it to the last physically non-
zero area before the reserved slice (from slice 0 to slice 6 or
unallocated space).

The efi_reserved_sectors() function calculates number of sectors
needed to create the reserved partition. The reserved partition is
used by the operating system for internal purposes. The sector size
used is based on the device and is recorded in the efi_lbasize member
of the dkgpt_t structure indicated by the vtoc argument. A full
description of the dk_gpt_t structure appears later in the manual.

The fd argument refers to any slice on a raw disk, opened with
O_NDELAY. See open(2).

The nparts argument specifies the number of desired partitions.

The vtoc argument is a dk_gpt_t structure that describes an EFI
partition table and contains at least the following members:

uint_t efi_version; /* set to EFI_VERSION_CURRENT */
uint_t efi_nparts; /* no. of partitions in efi_parts */
uint_t efi_lbasize; /* size of block in bytes */
diskaddr_t efi_last_lba; /* last block on the disk */
diskaddr_t efi_first_u_lba; /* first block after labels */
diskaddr_t efi_last_u_lba; /* last block before backup labels */
struct dk_part efi_parts[]; /* array of partitions */

Protective Master Boot Record

When a disk receives an EFI label, a protective MBR (PMBR) is also
written containing a single partition of type EEh and spanning the
entire disk (up to the limit of what can be represented in an MBR).
By default that partition is placed in slot 0 of the PMBR and not
marked as active. Some BIOS implementations contain bugs that require
the entry to be placed into a different slot or to be made active in
order for the system to boot successfully. The default behaviour is
modified for systems with known firmware bugs, refer to
/usr/share/hwdata/efi.fixes for more information.

RETURN VALUES

Upon successful completion, efi_alloc_and_init() returns 0. Otherwise
it returns VT_EIO if an I/O operation to the disk fails.

Upon successful completion, efi_alloc_and_read() returns a positive
integer indicating the slice index associated with the open file
descriptor. Otherwise, it returns a negative integer to indicate one
of the following:

VT_EIO
An I/O error occurred.

VT_ERROR
An unknown error occurred.

VT_EINVAL
An EFI label was not found.

The efi_reserved_sectors() function always returns the number of
reserved sectors required. It will always succeed.

Upon successful completion, efi_write() returns 0. Otherwise, it
returns a negative integer to indicate one of the following:

VT_EIO
An I/O error occurred.

VT_ERROR
An unknown error occurred.

VT_EINVAL
The label contains incorrect data.

Upon successfully completion, efi_use_whole_disk() returns 0.
Otherwise, it returns a negative integer to indicate one of the
following:

VT_EIO
An I/O error occurred.

VT_ERROR
An unknown error occurred.

VT_EINVAL
The label contains incorrect data.

VT_ENOSPC
Space out of label was not found.

USAGE

The EFI label is used on disks with more than 1^32-1 blocks. For
compatibility reasons, the read_vtoc(3EXT) and write_vtoc() functions
should be used on smaller disks. The application should attempt the
read_vtoc() or write_vtoc() call, check for an error of VT_ENOTSUP,
then call the analogous EFI function.

ATTRIBUTES