From dd0c91e98ed219435010dc9714f3f40137f0d418 Mon Sep 17 00:00:00 2001 From: Vladimir 'phcoder' Serbinenko Date: Thu, 22 Dec 2011 17:43:51 +0100 Subject: [PATCH] * docs/grub.texi (Loopback booting): New section. --- ChangeLog | 6 +++++- docs/grub.texi | 26 ++++++++++++++++++++++++++ 2 files changed, 31 insertions(+), 1 deletion(-) diff --git a/ChangeLog b/ChangeLog index e8588f0a1..69ccd49fe 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,4 +1,8 @@ -2011-12-19 Keshav P R +2011-12-22 Vladimir Serbinenko + + * docs/grub.texi (Loopback booting): New section. + +2011-12-22 Keshav P R * util/grub-mkstandalone.in: Fix minor typo errors. diff --git a/docs/grub.texi b/docs/grub.texi index f2e19cc74..b8d59d7d9 100644 --- a/docs/grub.texi +++ b/docs/grub.texi @@ -784,6 +784,7 @@ magic. @menu * General boot methods:: How to boot OSes with GRUB generally +* Loopback booting:: Notes on booting from loopbacks * OS-specific notes:: Notes on some operating systems @end menu @@ -855,6 +856,31 @@ required. @xref{DOS/Windows}. Chain-loading is only supported on PC BIOS and EFI platforms. +@node Loopback booting +@section Loopback booting +GRUB is able to read from an image (be it one of CD or HDD) stored on +any of its accessible storages (refer to @pxref{loopback} command). +However the OS itself should be able to find its root. This usually +involves running a userspace program running before the real root +is discovered. This is achieved by GRUB loading a specially made +small image and passing it as ramdisk to the kernel. This is achieved +by commands @command{kfreebsd_module}, @command{knetbsd_module_elf}, +@command{kopenbsd_ramdisk}, @command{initrd} (@pxref{initrd}), +@command{initrd16} (@pxref{initrd}), @command{multiboot_module}, +@command{multiboot2_module} or @command{xnu_ramdisk} +depending on the loader. Note that for knetbsd the image must be put +inside miniroot.kmod and the whole miniroot.kmod has to be loaded. In +kopenbsd payload this is disabled by default. Aditionally behaviour of +initial ramdisk depends on command line options. Several distributors provide +the image for this purpose or it's integrated in their standard ramdisk and +activated by special option. Consult your kernel and distribution manual for +more details. Other loaders like appleloader, chainloader (BIOS, EFI, coreboot), +freedos, ntldr and plan9 provide no possibility of loading initial ramdisk and +as far as author is aware the payloads in question don't support either initial +ramdisk or discovering loopback boot in other way and as such not bootable this +way. Please consider alternative boot methods like copying all files +from the image to actual partition. Consult your OS documentation for +more details @node OS-specific notes @section Some caveats on OS-specific issues -- 2.39.2