这次在有两块硬盘的机器上双系统安装 ubuntu，遇到了一些以前没有的情况

了解到两个以前没听过的名词

EFI vs BIOS

gpt vs mbr 两种分区表

参考链接二里还提到了快速启动安全启动过

详细介绍了 MBR+ BIOS 启动以及 GPTF分区的格式

http://www.iruanmi.com/what-is-gpt-and-what-is-uefi/

http://tieba.baidu.com/p/3754146793

这篇文章介绍了 uefi 的启动方法和启动顺序调整

http://blog.sina.com.cn/s/blog_53918a450102uzi6.html

UEFI的两种启动模式

https://help.ubuntu.com/community/Installation/FromUSBStick

UEFI 模式安装 ubuntu 的流程官方文档

https://help.ubuntu.com/community/UEFI

Installing Ubuntu in UEFI mode

The following sections describe how to install Ubuntu in UEFI mode, either because you‘re single-booting and want to try this boot mode or because you‘re dual-booting with another OS that‘s already installed in this mode.

Case when Ubuntu must be installed in UEFI mode

Having a PC with UEFI firmware does not mean that you need to install Ubuntu in UEFI mode. What is important is below:

if the other systems (Windows Vista/7/8, GNU/Linux...) of your computer are installed in UEFI mode, then you must install Ubuntu in UEFI mode too.
if the other systems (Windows, GNU/Linux...) of your computer are installed in Legacy (not-UEFI) mode, then you must install Ubuntu in Legacy mode too. Eg if your computer is old (<2010), is 32bits, or was
sold with a pre-installed Windows XP.
if Ubuntu is the only operating system on your computer, then it does not matter whether you install Ubuntu in UEFI mode or not.

我的机器上之前的windows 应该是 legacy mode 的，但是自动安装的 ubuntu却是 UEFI的

情况应该是像这样

https://help.ubuntu.com/community/Installation/FromUSBStick#Ubuntu_single_boot_in_UEFI_mode

Ubuntu single boot in UEFI mode

Single boot Ubuntu systems are still often installed in BIOS/CSM mode. Normally you install in UEFI mode because Windows is installed
in UEFI mode and you want to dual boot. But it is possible to install Ubuntu (and the flavours Kubuntu Lubuntu, Xubuntu) as a single boot system in UEFI mode too, which can
be useful for two purposes

to keep the systems separated,
Ubuntu in one drive and Windows in another drive (so it will actually be a dual boot system, but not during the installation).
Probably stable when installed in an internal drive.
----》比较符合我的安装情况
to make a portable installed Ubuntu USB pendrive for UEFI mode (portable alias works
in many computers). Not stable when installed in an external drive (USB stick).

所以系统安装时相当于是 single mode 的方式，但为什么没有给我默认安装成 legacy 方式呢。看来是这个 live disk 系统启动的时候就是通过 uefi 的方式启动的

https://help.ubuntu.com/community/Installation/FromUSBStick#Test_if_running_in_UEFI_mode

https://help.ubuntu.com/community/UEFI#Identifying_if_the_computer_boots_the_Ubuntu_DVD_in_UEFI_mode ----》》》我的 usb 的系统根据这个判断，是通过 efi模式启动的

General principles

To install Ubuntu in UEFI mode:

Use a 64bit disk of Ubuntu. (Ubuntu32bit
cannot be easily installed in UEFI mode. This is a problem if 32-bit UEFI is the only way your computer can boot, e.g. if you have a modern Intel Atom based laptop. In this case, you will need a
complicated work-around.)
In your firmware, disable
QuickBoot/FastBoot and Intel
Smart Response Technology (SRT). If you have Windows 8, also disable
Fast Startup.
You might want to use an EFI-only
image to avoid troubles with mistakenly booting the image and installing Ubuntu in BIOS mode.
Use a supported version of Ubuntu. Support for UEFI appeared in 11.10, but has become more reliable in next versions. Support for UEFISecureBoot appeared
in 12.10 and 12.04.2.
Set up your firmware (BIOS) to boot the disk in UEFI mode (see the "Identifying
if the computer boots the HDD in UEFI mode" paragraph below)
Then:
- nothing special is required if you use the automatic installer of Ubuntu ("Install Ubuntu alongside others" or "Erase the disk and install Ubuntu"). Important: if you have a pre-installed Windows and you want to keep it, do
  not choose "Erase the disk and install Ubuntu". ---》我选的是 erase，不过是另外一块盘
- if you use the manual partitioning ("Something else"), the difference is that you will have to set the /boot/efi mount point to the UEFI partition.
  And if there was not any UEFI partition on your HDD, you first will have to create it (see the "Creating
  an UEFI partition" paragraph below).

Set up the firmware in UEFI or BIOS/CSM/Legacy mode

Some recent computers (>2011) allow you to set up the computer to boot either in UEFI mode or in BIOS/CSM/Legacy (not-EFI) mode. The way to adjust this setting depends on the computers, but generally this setting is located in the "Boot order" tab of the BIOS
(to access the BIOS screens, it is generally necessary to press a key during the PC startup). It can also often be set on a per-boot basis by hitting a function key (F8 and F10 are common choices) soon after you power on the computer.

Note: Some UEFIs (e.g. American Megatrends‘ "Aptio", found on the Asus vivobook series) call Legacy mode "Compatibility Support Module" or simply "CSM".

Remark: Some UEFIs enable one to set up the boot mode for the optical drive separately from the boot mode for the HDD.

For example, below:

the "UEFI Hitachi" line allows to boot the HDD in UEFI mode,
the "P1: Hitachi" line allows to boot the HDD in Legacy (not-UEFI) mode,
the "P3: DVD" line allows to boot the Ubuntu CD in Legacy mode
the "UEFI: USB" line allows to boot the Ubuntu liveUSB in UEFI mode.

Here is a 2nd example of UEFI boot mode setting, where the "Boot Mode" parameter enables one to choose the boot mode ("UEFI" or "Legacy") for all media (hard disk, CD, USB...) at the same time.

Some other UEFIs propose an "UEFI/Legacy Boot:" option with the following choices: [Legacy only], [UEFI only] and [Both]. This last one boots in UEFI mode when possible, then in Legacy mode if no UEFI files are detected.

！！！！！！！！

Note that in a UEFI-mode installation, Ubuntu
will not ask
you where to install the boot loader. If it does, or if it complains about
the lack of a BIOS
Boot Partition, you‘ve probably accidentally booted in BIOS/CSM/legacy mode.

关于 ubuntu 的分区模式

NONE-GPT & GPT 分区

https://help.ubuntu.com/community/DiskSpace

Required partitions

Overview

The easiest partitioning scheme, on a non-GPT disk, is simply a root partition and a swap partition.

Name	Size
`swap`	size of RAM
`/`	the rest of the disk

If the disk is GPT type (this can be checked via the "sudo parted -l" command), you must also add a BIOS-Boot or an EFI
partition depending on the boot mode of your BIOS.

Name	Size
`BIOS-boot` or `EFI`	see below
`swap`	size of RAM
`/`	the rest of the disk

On some computers, a separate /boot partition may also be required.

See paragraphs below.

Root partition (always required)

Mount point: /
Type: Linux type (generally EXT4)
Description: the root partition contains by default all your system files, program settings and documents.
Size: minimum is 8 GB. It is recommended to make it at least 15 GB. Warning: your system will be blocked if the root partition is full.

Swap (very recommended)

Mount point: none
Type: SWAP
Description: see SwapFaq.
Size: size of your RAM.

BIOS-Boot or EFI partition (required on GPT disks)

If you want to install Ubuntu on a GPT disk (you can check it via the ‘sudo parted -l‘ command), you will need either an
EFI partition (if your BIOS is set up in EFI mode) or a BIOS-Boot partition (if your BIOS is set up in Legacy mode).

BIOS-Boot partition:

Mount point: none
Type: no filesystem
Description: the BIOS-boot partition contains GRUB 2‘s core. It is necessary if you install Ubuntu on a GPT disk, and
if the firmware (BIOS) is set up in Legacy (not EFI) mode.
It must be located at the start of a GPT disk, and have a "bios_grub" flag.
Size: 1MB.

EFI partition:

Mount point: /boot/efi (no need to set up this mount point as the installer will do it automatically)
Type: FAT (generally FAT32)
Description: the EFI partition (also called ESP) contains some boot files.
It is necessary if the firmware (BIOS) is set up to boot the HDD in EFI mode
(which is default on more and more modern, > year 2011 computers).
It must be located at the start of a GPT disk, and have a "boot" flag.
Size: 100~250MB

https://wiki.archlinux.org/index.php/Unified_Extensible_Firmware_Interface

https://en.wikipedia.org/wiki/Unified_Extensible_Firmware_Interface#UEFI_booting

https://en.wikipedia.org/wiki/EFI_system_partition

The EFI System partition needs to be formatted with a file system whose specification is maintained as part of
the UEFI specification; the file system itself is based on the FAT file
system but is independent from the original FAT specification.^[1] The globally
unique identifier (GUID) for the EFI System partition in the GUID
Partition Table (GPT) scheme is C12A7328-F81F-11D2-BA4B-00A0C93EC93B,
while its ID in the MBR
partition table scheme is 0xEF.Both
GPT- and MBR-partitioned disks can contain an EFI System partition, as UEFI firmware is required to support both partitioning schemes. Also, El
Torito bootable format for CD-ROMs and DVDs is
supported.^[3]

UEFI provides backward compatibility with legacy systems by
reserving the first block (sector) of the partition for compatibility code, effectively creating a legacy boot
sector. On legacy BIOS-based systems, the first sector of a partition is loaded into memory
and execution is transferred to this code. UEFI firmware does not execute the code in the Master
Boot Record (MBR), except when booting in legacy BIOS mode through the Compatibility
Support Module (CSM).^[3]

The UEFI specification requires MBR partition tables to be fully supported.^[3] However,
some UEFI implementations immediately switch to the BIOS-based CSM booting upon detecting certain types of partition table on the boot disk, effectively preventing UEFI booting to be performed from EFI System partitions contained on MBR-partitioned disks.^[4]

UEFI firmware supports booting from removable storage devices such as USB flash
drives. For that purpose, a removable device needs to be formatted with a FAT12, FAT16 or FAT32 file
system, while a boot loader needs to be stored according to the standard ESP file hierarchy, or by providing a complete path of a boot loader to the system‘s boot manager.^[3]

https://wiki.archlinux.org/index.php/Boot_loaders

Both BIOS and UEFI boot loaders

GRUB

GRUB is more feature-rich and supports more complex scenarios.
Its configuration file(s) is more similar to ‘sh‘ scripting language, and can be automatically generated.

Syslinux

Syslinux is (currently) limited to loading only
files from the partition where it was installed. An example configuration can be found in Syslinux#Examples.

UEFI-only boot loaders

Linux Kernel EFISTUB

The Linux kernel can be booted directly using the built-in EFI stub loader. See EFISTUB.

systemd-boot

systemd includes an EFI bootloader which provides a text menu for booting EFISTUB kernels. See systemd-boot.

rEFInd

rEFInd is a UEFI Boot Manager which provides a graphical menu for booting EFISTUB kernels. See rEFInd.

Clover

Clover is a UEFI Boot Manager which provides native resolution GUI for booting EFISTUB kernels. See Clover.

ELILO

Warning: ELILO upstream has clarified that it is no longer in active development, meaning no new features will be added and only bug-fixes are released. Seehttps://sourceforge.net/mailarchive/message.php?msg_id=31524008 for
more information. ELILO is not officially supported by Arch developers.

ELILO is the UEFI version of the BIOS-only LILO. Its config
file elilo.conf is similar to LILO‘s
config file. Upstream provided compiled binaries are available athttp://sourceforge.net/projects/elilo/ and
an AUR package at elilo-efi^AUR.

BIOS-only boot loaders

Warning: None of the options presented here are officialy supported in Arch Linux.

GRUB Legacy

GRUB Legacy (also known as grub-0.97), is the legacy, BIOS-only branch of GRUB.
See GRUB Legacy.

LILO

See LILO.

https://wiki.archlinux.org/index.php/GUID_Partition_Table#Bootloader_Support

Bootloader Support

UEFI systems

All UEFI Bootloaders support GPT disks since GPT is a part of UEFI Specification and thus mandatory for UEFI boot. See Boot
loaders for more information.

BIOS systems

While GPT support on BIOS systems is theoretically possible it sometimes isn‘t practical and other times there are complete incompatibilities. Technically the BIOS is only supposed to execute the code on the MBR, therefore leaving the possibility of differing
partitioning schemes... However a BIOS may do additional checks including: checking a MBR‘s integrity, and possibly even for a MBR partition table (though usually only the first partition). If this is a case, a number of workarounds exist that may be able
to repair the problem (listed below).

Warning: For Windows, there is no support for booting from a BIOS/GPT partitioning scheme. If you have already installed Windows with a BIOS/MBR partitioning scheme do not convert the drive to GPT! Windows
will fail to boot if this is done - irrespective of the bootloader used to chainload Windows. One can either install Windows in UEFI mode and use an UEFI
bootloader (which uses GPT), or possibly restore/install Windows on a BIOS/GPT hybrid MBR (see partitioning examples).

Bootloaders that support GPT/BIOS partitioning scheme bootloading:

Not suported: GRUB Legacy and LILO.

Workarounds

A few workarounds may help boot a BIOS/GPT partitioning scheme; however, before trying these, try booting a BIOS/GPT partitioning scheme with the bootloaders standard procedure. If it doesn‘t work, these may help boot them (read
this for full reference):

Set the boot flag on the protective MBR partition (type 0xEE) . This can be done with parted /dev/sdX and disk_toggle pmbr_boot or using sgdisk /dev/sdX --attributes=1:set:2.
Be sure there is no EFI system partition
Create a hybrid MBR. This will be needed for a BIOS that looks for a valid MBR partition (see example below).
Recompute CHS (Cylinder/Head/Sector) values in the protective MBR. GPT does not use these values but the protective MBR may need to be calibrated to them to work for those BIOS that test them.
A second disk that has a valid MBR table may signify to the BIOS that it is alright to execute the code on the protective MBR.
Many computers since 2011 may have support for an EFI booting if wanting from a BIOS option.

我的安装情况

第一块硬盘安装了 windows

第二块盘准备用来装 linux

创建了可启动的 ubuntu usb livecd 用的镜像是ubuntu-14.04.4-desktop-amd64.iso

开机

以前如果需要从 usb 引导来安装系统，需要进入bios修改系统启动介质的顺序，但是这次很奇怪。插上u盘重启后直接进入 u盘的系统里面了

如果选 ERASE+ LVM 然后硬盘选择 sdb - > install now, 进入界面

如果 installation type 不选择 lvm 的话

都会默认生成一个 EFIBOOT 盘

-----------------------------

如果

installation type 选something else 则会进入分区详情

按照以前装双系统的经验是，会在 sdb 创建 root分区 / ext4 以及 swap 分区

然后 boot loader device，如果选 sda，那么就会把 grub 装到磁盘一，然后启动时，可以从启动菜单选择进入linux（默认）或者windows

如果boot loader device 选 sdb 的话，那么默认 linux 就启动不了，需要在 bios 把磁盘二的启动顺序调到前面，才可以启动linux，启动菜单里也没有windows。此时 windows 和 linux 的启动是完全独立的

=====

但是因为这个机器的主板好像是支持 efi 的，我选择了默认的非 lvm 安装方式后，系统就开始自己安装，

按照自动安装模式下上图系统提示的 sdb 分区信息可以看出，自动都建立了一个 EFIboot 分区，这个就是 EFI 模式下bootloader 安装的地方？？？所以上文

https://help.ubuntu.com/community/UEFI#Performing_the_Installation 里面说，在 EFI模式安装是不会问在哪里装bootloader 的，因为只能安装在 EFI 分区里？

安装完成后，我就重启机器，很奇怪，开机画面之后系统马上就进入 ubuntu 了，试图用 fdisk 查看分区表，结过 sdb 的分区看不了？说是用了 gpt分区，只能用 parted 工具来查看，这才知道这次的分区格式竟然也和以前不一样了。

--- 那么怎么进入 windows呢？

我现在使用的办法是，一闪而过的开机节目里最下排有提示

DEL bios setup

f9 system information

f12 boot menu

我按住 f12 然后会出现硬盘的列表，选择装了windows 的盘一，就会顺利进入 windows

问题是：

为什么默认会进入 ubuntu 而不是 windows 呢，这跟 efi 又有什么关系呢

好像这个 efi 也可以配置成 enabled 或者是使用 legacy ？

下面就开始到处搜索关于 EFI 还有 GPT 的相关知识

===============

似乎 windows 8 以后的windows 才会出现用 efi 引导的方式来安装？

http://blog.163.com/[email protected]/blog/static/3571595020146192136557/

这个是单硬盘 win 7 安装双系统 ubuntu

但是需要将 uefi 设置成 legacy only，那样的话就变成跟传统用 MBR 分区表建立分区然后通过 bios 启动的过程是一样的了

否则安装的时候 ubuntu 就识别不出 windows下已经通过 mbr 建立的分区？？？奇怪我安装的时候倒是可以看到 windows 的分区的。

不过没有尝试如果不建立 EFIBOOT 分区的话能不能安成功

参考

http://os.51cto.com/art/201405/439158.htm

给了一个详细的例子不过是一块硬盘而且是 windows 8 + ubuntu 14

安装完后还需要在 ubuntu 和 windows 都进行启动修复才可以出现多选项的启动菜单否则直接进入 windows

时间： 2024-08-19 05:11:18

支持 efi 的主板双系统安装 ubuntu - 学习 EFI 和 gpt