GRUB 2 Menu

 
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Old 11-13-2016
GRUB 2 Menu

The quick & dirty question I have is... What app/script actually loads the Grub 2 menu system? And where is it located?

The longer question is I understand the core.img is loaded onto the first 63 sectors (stage 1.5) and after it loads I starts the stage 2 Grub bootloader which loads the Menu system. I've searched to try & figure this out but all I keep seeing are references to an ambiguous "Grub 2 bootloader"... What is the exact process of transferring the boot process between stage 1.5 and stage 2?

Can someone PLEASE help me with the specifics... at this point finding the answer has kicked in my OCD & it's driving me crazy.... Thanks!!!
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bootadm(1M)						  System Administration Commands					       bootadm(1M)

NAME
bootadm - manage bootability of GRUB-enabled operating system SYNOPSIS
/sbin/bootadm update-archive [-vn] [-R altroot [-p platform]] /sbin/bootadm list-archive [-vn] [-R altroot [-p platform]] x86 only /sbin/bootadm set-menu [-R altroot [-p platform]] key=value /sbin/bootadm list-menu [-R altroot [-p platform]] DESCRIPTION
The bootadm command manages the boot archive and, with x86 boot environments, the GRUB (GRand Unified Bootloader) menu. The update-archive option provides a way for user to update the boot archive as a preventative measure or as part of a recovery procedure. The set-menu sub- command allows you to switch the auto-boot timeout and default boot entry in the GRUB menu. The list-menu subcommand displays the location of the GRUB menu and the current GRUB menu entries. While the typical location of the GRUB menu is /boot/grub/menu.lst, depending on the install method used the active GRUB menu might be located somewhere else. Use the list-menu subcommand to locate the active GRUB menu. For example, if a system was installed using Live Upgrade, the GRUB menu might not be located in the current boot environment. See the EXAMPLES section for typical output from the list-menu option. Note that OpenBoot PROM (OBP)-based machines, such as SPARC systems, do not use GRUB and have no boot menu manageable by bootadm. The bootadm command determines dynamically the options supported by the image to be managed, so that bootadm invoked on one platform can be used to manage diskless clients of a different platform type. SUBCOMMANDS
The bootadm command has the following subcommands: update-archive Updates current boot archive if required. Applies to both SPARC and x86 platforms. list-archive Lists the files and directories to be included in the boot archive. Applies to both SPARC and x86 platforms. set-menu Maintain the GRUB menu. The current GRUB menu is boot/grub/menu.lst, relative to root. Do not depend on this location, because it is subject to change. Applies to x86 platforms only. list-menu Lists the location of the active GRUB menu, as well as the current GRUB menu entries. This includes the autoboot-timeout, the default entry number, and the title of each entry. Applies to x86 platforms only. OPTIONS
The bootadm command has the following options: -v In an update-archive operation, stale files are displayed on stderr. -n In an update-archive operation, archive content is checked but not updated. -p platform The platform, or machine hardware class, of the client. The platform type can only be specified together with -R, and is generally use- ful only for managing a diskless client where the client is of a different platform class than the server. Platform must be one of i86pc, sun4u, or sun4v. -R altroot Operation is applied to an alternate root path. Note - The root file system of any non-global zones must not be referenced with the -R option. Doing so might damage the global zone's file system, might compromise the security of the global zone, and might damage the non-global zone's file system. See zones(5). key=value Possible values are: default=entrynum The item number (for example, 0, 1, or 2) in the GRUB menu designating the operating system to boot when the timer expires. timeout=seconds The number of seconds before the operating system designated by the default item number is booted. If the value is -1, auto boot is disabled. EXAMPLES
Example 1 Updating the Current Boot Archive The following command updates the current boot archive: # bootadm update-archive Example 2 Updating the Boot Archive on an Alternate Root The following command updates the boot archive on an alternate root: # bootadm update-archive -R /a Example 3 Listing Installed OS Instances The following command lists the installed operating system instances in a GRUB menu: # bootadm list-menu default=0 timeout=10(0) Solaris10(1) Solaris10 Failsafe(2) Linux Example 4 Switching Default Boot Entry The following command refers to the menu displayed in the previous example. The user selects Linux (item 2). # bootadm set-menu default=2 Example 5 Listing GRUB Menu Entries and Location of GRUB Menu The following command lists the GRUB menu entries and the location of the GRUB menu: # bootadm list-menu The location for the active GRUB menu is: /stubboot/boot/grub/menu.lst default 0 timeout 10 0 Solaris10 1 Solaris10 failsafe 2 Linux Example 6 Displaying Location of GRUB Menu The following command displays the location of the GRUB menu: # bootadm list-menu The location for the active GRUB menu is: /dev/dsk/c0t1d0s0 (not mounted) The filesystem type of the menu device is <ufs> default 2 timeout 10 0 c0t1d0s3 1 c0t1d0s3 failsafe 2 Solaris10 3 Solaris10 failsafe In this example, the active GRUB menu is located on a device which is not mounted. To access the GRUB menu, mount the device and access the GRUB menu at <mountpoint>/boot/grub/menu.lst. EXIT STATUS
The following exit values are returned: 0 The command completed successfully. 1 The command exited due to an error. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsu | +-----------------------------+-----------------------------+ |Interface Stability |Committed | +-----------------------------+-----------------------------+ SEE ALSO
boot(1M), installgrub(1M), attributes(5) Consult the GRUB home page, under: http://www.gnu.org/ SunOS 5.11 25 Apr 2008 bootadm(1M)