[PATCH v4 19/20] x86: doc: Split out manual booting into its own file
Simon Glass
sjg at chromium.org
Wed Aug 23 23:10:36 CEST 2023
Move this out of the main file since for simple users it is easier to
rely on standard boot.
Signed-off-by: Simon Glass <sjg at chromium.org>
---
(no changes since v2)
Changes in v2:
- Add new patch
doc/arch/x86/index.rst | 1 +
doc/arch/x86/manual_boot.rst | 276 +++++++++++++++++++++++++++++++++++
doc/arch/x86/x86.rst | 272 +---------------------------------
3 files changed, 280 insertions(+), 269 deletions(-)
create mode 100644 doc/arch/x86/manual_boot.rst
diff --git a/doc/arch/x86/index.rst b/doc/arch/x86/index.rst
index 3dc19d603d4..69db0a5d648 100644
--- a/doc/arch/x86/index.rst
+++ b/doc/arch/x86/index.rst
@@ -9,3 +9,4 @@ x86
:maxdepth: 2
x86
+ manual_boot
diff --git a/doc/arch/x86/manual_boot.rst b/doc/arch/x86/manual_boot.rst
new file mode 100644
index 00000000000..ec069f2c397
--- /dev/null
+++ b/doc/arch/x86/manual_boot.rst
@@ -0,0 +1,276 @@
+Booting Ubuntu Manually
+-----------------------
+
+This shows a manual approach to booting Ubuntu without standard boot or the EFI
+interface.
+
+As an example of how to set up your boot flow with U-Boot, here are
+instructions for starting Ubuntu from U-Boot. These instructions have been
+tested on Minnowboard MAX with a SATA drive but are equally applicable on
+other platforms and other media. There are really only four steps and it's a
+very simple script, but a more detailed explanation is provided here for
+completeness.
+
+Note: It is possible to set up U-Boot to boot automatically using syslinux.
+It could also use the grub.cfg file (/efi/ubuntu/grub.cfg) to obtain the
+GUID. If you figure these out, please post patches to this README.
+
+Firstly, you will need Ubuntu installed on an available disk. It should be
+possible to make U-Boot start a USB start-up disk but for now let's assume
+that you used another boot loader to install Ubuntu.
+
+Use the U-Boot command line to find the UUID of the partition you want to
+boot. For example our disk is SCSI device 0::
+
+ => part list scsi 0
+
+ Partition Map for SCSI device 0 -- Partition Type: EFI
+
+ Part Start LBA End LBA Name
+ Attributes
+ Type GUID
+ Partition GUID
+ 1 0x00000800 0x001007ff ""
+ attrs: 0x0000000000000000
+ type: c12a7328-f81f-11d2-ba4b-00a0c93ec93b
+ guid: 9d02e8e4-4d59-408f-a9b0-fd497bc9291c
+ 2 0x00100800 0x037d8fff ""
+ attrs: 0x0000000000000000
+ type: 0fc63daf-8483-4772-8e79-3d69d8477de4
+ guid: 965c59ee-1822-4326-90d2-b02446050059
+ 3 0x037d9000 0x03ba27ff ""
+ attrs: 0x0000000000000000
+ type: 0657fd6d-a4ab-43c4-84e5-0933c84b4f4f
+ guid: 2c4282bd-1e82-4bcf-a5ff-51dedbf39f17
+ =>
+
+This shows that your SCSI disk has three partitions. The really long hex
+strings are called Globally Unique Identifiers (GUIDs). You can look up the
+'type' ones `here`_. On this disk the first partition is for EFI and is in
+VFAT format (DOS/Windows)::
+
+ => fatls scsi 0:1
+ efi/
+
+ 0 file(s), 1 dir(s)
+
+
+Partition 2 is 'Linux filesystem data' so that will be our root disk. It is
+in ext2 format::
+
+ => ext2ls scsi 0:2
+ <DIR> 4096 .
+ <DIR> 4096 ..
+ <DIR> 16384 lost+found
+ <DIR> 4096 boot
+ <DIR> 12288 etc
+ <DIR> 4096 media
+ <DIR> 4096 bin
+ <DIR> 4096 dev
+ <DIR> 4096 home
+ <DIR> 4096 lib
+ <DIR> 4096 lib64
+ <DIR> 4096 mnt
+ <DIR> 4096 opt
+ <DIR> 4096 proc
+ <DIR> 4096 root
+ <DIR> 4096 run
+ <DIR> 12288 sbin
+ <DIR> 4096 srv
+ <DIR> 4096 sys
+ <DIR> 4096 tmp
+ <DIR> 4096 usr
+ <DIR> 4096 var
+ <SYM> 33 initrd.img
+ <SYM> 30 vmlinuz
+ <DIR> 4096 cdrom
+ <SYM> 33 initrd.img.old
+ =>
+
+and if you look in the /boot directory you will see the kernel::
+
+ => ext2ls scsi 0:2 /boot
+ <DIR> 4096 .
+ <DIR> 4096 ..
+ <DIR> 4096 efi
+ <DIR> 4096 grub
+ 3381262 System.map-3.13.0-32-generic
+ 1162712 abi-3.13.0-32-generic
+ 165611 config-3.13.0-32-generic
+ 176500 memtest86+.bin
+ 178176 memtest86+.elf
+ 178680 memtest86+_multiboot.bin
+ 5798112 vmlinuz-3.13.0-32-generic
+ 165762 config-3.13.0-58-generic
+ 1165129 abi-3.13.0-58-generic
+ 5823136 vmlinuz-3.13.0-58-generic
+ 19215259 initrd.img-3.13.0-58-generic
+ 3391763 System.map-3.13.0-58-generic
+ 5825048 vmlinuz-3.13.0-58-generic.efi.signed
+ 28304443 initrd.img-3.13.0-32-generic
+ =>
+
+The 'vmlinuz' files contain a packaged Linux kernel. The format is a kind of
+self-extracting compressed file mixed with some 'setup' configuration data.
+Despite its size (uncompressed it is >10MB) this only includes a basic set of
+device drivers, enough to boot on most hardware types.
+
+The 'initrd' files contain a RAM disk. This is something that can be loaded
+into RAM and will appear to Linux like a disk. Ubuntu uses this to hold lots
+of drivers for whatever hardware you might have. It is loaded before the
+real root disk is accessed.
+
+The numbers after the end of each file are the version. Here it is Linux
+version 3.13. You can find the source code for this in the Linux tree with
+the tag v3.13. The '.0' allows for additional Linux releases to fix problems,
+but normally this is not needed. The '-58' is used by Ubuntu. Each time they
+release a new kernel they increment this number. New Ubuntu versions might
+include kernel patches to fix reported bugs. Stable kernels can exist for
+some years so this number can get quite high.
+
+The '.efi.signed' kernel is signed for EFI's secure boot. U-Boot has its own
+secure boot mechanism - see `this`_ & `that`_. It cannot read .efi files
+at present.
+
+To boot Ubuntu from U-Boot the steps are as follows:
+
+1. Set up the boot arguments. Use the GUID for the partition you want to boot::
+
+ => setenv bootargs root=/dev/disk/by-partuuid/965c59ee-1822-4326-90d2-b02446050059 ro
+
+Here root= tells Linux the location of its root disk. The disk is specified
+by its GUID, using '/dev/disk/by-partuuid/', a Linux path to a 'directory'
+containing all the GUIDs Linux has found. When it starts up, there will be a
+file in that directory with this name in it. It is also possible to use a
+device name here, see later.
+
+2. Load the kernel. Since it is an ext2/4 filesystem we can do::
+
+ => ext2load scsi 0:2 03000000 /boot/vmlinuz-3.13.0-58-generic
+
+The address 30000000 is arbitrary, but there seem to be problems with using
+small addresses (sometimes Linux cannot find the ramdisk). This is 48MB into
+the start of RAM (which is at 0 on x86).
+
+3. Load the ramdisk (to 64MB)::
+
+ => ext2load scsi 0:2 04000000 /boot/initrd.img-3.13.0-58-generic
+
+4. Start up the kernel. We need to know the size of the ramdisk, but can use
+ a variable for that. U-Boot sets 'filesize' to the size of the last file it
+ loaded::
+
+ => zboot 03000000 0 04000000 ${filesize}
+
+Type 'help zboot' if you want to see what the arguments are. U-Boot on x86 is
+quite verbose when it boots a kernel. You should see these messages from
+U-Boot::
+
+ Valid Boot Flag
+ Setup Size = 0x00004400
+ Magic signature found
+ Using boot protocol version 2.0c
+ Linux kernel version 3.13.0-58-generic (buildd at allspice) #97-Ubuntu SMP Wed Jul 8 02:56:15 UTC 2015
+ Building boot_params at 0x00090000
+ Loading bzImage at address 100000 (5805728 bytes)
+ Magic signature found
+ Initial RAM disk at linear address 0x04000000, size 19215259 bytes
+ Kernel command line: "root=/dev/disk/by-partuuid/965c59ee-1822-4326-90d2-b02446050059 ro"
+
+ Starting kernel ...
+
+U-Boot prints out some bootstage timing. This is more useful if you put the
+above commands into a script since then it will be faster::
+
+ Timer summary in microseconds:
+ Mark Elapsed Stage
+ 0 0 reset
+ 241,535 241,535 board_init_r
+ 2,421,611 2,180,076 id=64
+ 2,421,790 179 id=65
+ 2,428,215 6,425 main_loop
+ 48,860,584 46,432,369 start_kernel
+
+ Accumulated time:
+ 240,329 ahci
+ 1,422,704 vesa display
+
+Now the kernel actually starts (if you want to examine kernel boot up message on
+the serial console, append "console=ttyS0,115200" to the kernel command line)::
+
+ [ 0.000000] Initializing cgroup subsys cpuset
+ [ 0.000000] Initializing cgroup subsys cpu
+ [ 0.000000] Initializing cgroup subsys cpuacct
+ [ 0.000000] Linux version 3.13.0-58-generic (buildd at allspice) (gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1) ) #97-Ubuntu SMP Wed Jul 8 02:56:15 UTC 2015 (Ubuntu 3.13.0-58.97-generic 3.13.11-ckt22)
+ [ 0.000000] Command line: root=/dev/disk/by-partuuid/965c59ee-1822-4326-90d2-b02446050059 ro console=ttyS0,115200
+
+It continues for a long time. Along the way you will see it pick up your
+ramdisk::
+
+ [ 0.000000] RAMDISK: [mem 0x04000000-0x05253fff]
+ ...
+ [ 0.788540] Trying to unpack rootfs image as initramfs...
+ [ 1.540111] Freeing initrd memory: 18768K (ffff880004000000 - ffff880005254000)
+ ...
+
+Later it actually starts using it::
+
+ Begin: Running /scripts/local-premount ... done.
+
+You should also see your boot disk turn up::
+
+ [ 4.357243] scsi 1:0:0:0: Direct-Access ATA ADATA SP310 5.2 PQ: 0 ANSI: 5
+ [ 4.366860] sd 1:0:0:0: [sda] 62533296 512-byte logical blocks: (32.0 GB/29.8 GiB)
+ [ 4.375677] sd 1:0:0:0: Attached scsi generic sg0 type 0
+ [ 4.381859] sd 1:0:0:0: [sda] Write Protect is off
+ [ 4.387452] sd 1:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
+ [ 4.399535] sda: sda1 sda2 sda3
+
+Linux has found the three partitions (sda1-3). Mercifully it doesn't print out
+the GUIDs. In step 1 above we could have used::
+
+ setenv bootargs root=/dev/sda2 ro
+
+instead of the GUID. However if you add another drive to your board the
+numbering may change whereas the GUIDs will not. So if your boot partition
+becomes sdb2, it will still boot. For embedded systems where you just want to
+boot the first disk, you have that option.
+
+The last thing you will see on the console is mention of plymouth (which
+displays the Ubuntu start-up screen) and a lot of 'Starting' messages::
+
+ * Starting Mount filesystems on boot [ OK ]
+
+After a pause you should see a login screen on your display and you are done.
+
+If you want to put this in a script you can use something like this::
+
+ setenv bootargs root=UUID=b2aaf743-0418-4d90-94cc-3e6108d7d968 ro
+ setenv boot zboot 03000000 0 04000000 \${filesize}
+ setenv bootcmd "ext2load scsi 0:2 03000000 /boot/vmlinuz-3.13.0-58-generic; ext2load scsi 0:2 04000000 /boot/initrd.img-3.13.0-58-generic; run boot"
+ saveenv
+
+The \ is to tell the shell not to evaluate ${filesize} as part of the setenv
+command.
+
+You can also bake this behaviour into your build by hard-coding the
+environment variables if you add this to minnowmax.h:
+
+.. code-block:: c
+
+ #undef CONFIG_BOOTCOMMAND
+ #define CONFIG_BOOTCOMMAND \
+ "ext2load scsi 0:2 03000000 /boot/vmlinuz-3.13.0-58-generic; " \
+ "ext2load scsi 0:2 04000000 /boot/initrd.img-3.13.0-58-generic; " \
+ "run boot"
+
+ #undef CFG_EXTRA_ENV_SETTINGS
+ #define CFG_EXTRA_ENV_SETTINGS "boot=zboot 03000000 0 04000000 ${filesize}"
+
+and change CONFIG_BOOTARGS value in configs/minnowmax_defconfig to::
+
+ CONFIG_BOOTARGS="root=/dev/sda2 ro"
+
+.. _here: https://en.wikipedia.org/wiki/GUID_Partition_Table
+.. _this: http://events.linuxfoundation.org/sites/events/files/slides/chromeos_and_diy_vboot_0.pdf
+.. _that: http://events.linuxfoundation.org/sites/events/files/slides/elce-2014.pdf
diff --git a/doc/arch/x86/x86.rst b/doc/arch/x86/x86.rst
index e75b5a73ffc..c435225da4e 100644
--- a/doc/arch/x86/x86.rst
+++ b/doc/arch/x86/x86.rst
@@ -97,272 +97,9 @@ mtrr
Booting Ubuntu
--------------
-As an example of how to set up your boot flow with U-Boot, here are
-instructions for starting Ubuntu from U-Boot. These instructions have been
-tested on Minnowboard MAX with a SATA drive but are equally applicable on
-other platforms and other media. There are really only four steps and it's a
-very simple script, but a more detailed explanation is provided here for
-completeness.
-
-Note: It is possible to set up U-Boot to boot automatically using syslinux.
-It could also use the grub.cfg file (/efi/ubuntu/grub.cfg) to obtain the
-GUID. If you figure these out, please post patches to this README.
-
-Firstly, you will need Ubuntu installed on an available disk. It should be
-possible to make U-Boot start a USB start-up disk but for now let's assume
-that you used another boot loader to install Ubuntu.
-
-Use the U-Boot command line to find the UUID of the partition you want to
-boot. For example our disk is SCSI device 0::
-
- => part list scsi 0
-
- Partition Map for SCSI device 0 -- Partition Type: EFI
-
- Part Start LBA End LBA Name
- Attributes
- Type GUID
- Partition GUID
- 1 0x00000800 0x001007ff ""
- attrs: 0x0000000000000000
- type: c12a7328-f81f-11d2-ba4b-00a0c93ec93b
- guid: 9d02e8e4-4d59-408f-a9b0-fd497bc9291c
- 2 0x00100800 0x037d8fff ""
- attrs: 0x0000000000000000
- type: 0fc63daf-8483-4772-8e79-3d69d8477de4
- guid: 965c59ee-1822-4326-90d2-b02446050059
- 3 0x037d9000 0x03ba27ff ""
- attrs: 0x0000000000000000
- type: 0657fd6d-a4ab-43c4-84e5-0933c84b4f4f
- guid: 2c4282bd-1e82-4bcf-a5ff-51dedbf39f17
- =>
-
-This shows that your SCSI disk has three partitions. The really long hex
-strings are called Globally Unique Identifiers (GUIDs). You can look up the
-'type' ones `here`_. On this disk the first partition is for EFI and is in
-VFAT format (DOS/Windows)::
-
- => fatls scsi 0:1
- efi/
-
- 0 file(s), 1 dir(s)
-
-
-Partition 2 is 'Linux filesystem data' so that will be our root disk. It is
-in ext2 format::
-
- => ext2ls scsi 0:2
- <DIR> 4096 .
- <DIR> 4096 ..
- <DIR> 16384 lost+found
- <DIR> 4096 boot
- <DIR> 12288 etc
- <DIR> 4096 media
- <DIR> 4096 bin
- <DIR> 4096 dev
- <DIR> 4096 home
- <DIR> 4096 lib
- <DIR> 4096 lib64
- <DIR> 4096 mnt
- <DIR> 4096 opt
- <DIR> 4096 proc
- <DIR> 4096 root
- <DIR> 4096 run
- <DIR> 12288 sbin
- <DIR> 4096 srv
- <DIR> 4096 sys
- <DIR> 4096 tmp
- <DIR> 4096 usr
- <DIR> 4096 var
- <SYM> 33 initrd.img
- <SYM> 30 vmlinuz
- <DIR> 4096 cdrom
- <SYM> 33 initrd.img.old
- =>
-
-and if you look in the /boot directory you will see the kernel::
-
- => ext2ls scsi 0:2 /boot
- <DIR> 4096 .
- <DIR> 4096 ..
- <DIR> 4096 efi
- <DIR> 4096 grub
- 3381262 System.map-3.13.0-32-generic
- 1162712 abi-3.13.0-32-generic
- 165611 config-3.13.0-32-generic
- 176500 memtest86+.bin
- 178176 memtest86+.elf
- 178680 memtest86+_multiboot.bin
- 5798112 vmlinuz-3.13.0-32-generic
- 165762 config-3.13.0-58-generic
- 1165129 abi-3.13.0-58-generic
- 5823136 vmlinuz-3.13.0-58-generic
- 19215259 initrd.img-3.13.0-58-generic
- 3391763 System.map-3.13.0-58-generic
- 5825048 vmlinuz-3.13.0-58-generic.efi.signed
- 28304443 initrd.img-3.13.0-32-generic
- =>
-
-The 'vmlinuz' files contain a packaged Linux kernel. The format is a kind of
-self-extracting compressed file mixed with some 'setup' configuration data.
-Despite its size (uncompressed it is >10MB) this only includes a basic set of
-device drivers, enough to boot on most hardware types.
-
-The 'initrd' files contain a RAM disk. This is something that can be loaded
-into RAM and will appear to Linux like a disk. Ubuntu uses this to hold lots
-of drivers for whatever hardware you might have. It is loaded before the
-real root disk is accessed.
-
-The numbers after the end of each file are the version. Here it is Linux
-version 3.13. You can find the source code for this in the Linux tree with
-the tag v3.13. The '.0' allows for additional Linux releases to fix problems,
-but normally this is not needed. The '-58' is used by Ubuntu. Each time they
-release a new kernel they increment this number. New Ubuntu versions might
-include kernel patches to fix reported bugs. Stable kernels can exist for
-some years so this number can get quite high.
-
-The '.efi.signed' kernel is signed for EFI's secure boot. U-Boot has its own
-secure boot mechanism - see `this`_ & `that`_. It cannot read .efi files
-at present.
-
-To boot Ubuntu from U-Boot the steps are as follows:
-
-1. Set up the boot arguments. Use the GUID for the partition you want to boot::
-
- => setenv bootargs root=/dev/disk/by-partuuid/965c59ee-1822-4326-90d2-b02446050059 ro
-
-Here root= tells Linux the location of its root disk. The disk is specified
-by its GUID, using '/dev/disk/by-partuuid/', a Linux path to a 'directory'
-containing all the GUIDs Linux has found. When it starts up, there will be a
-file in that directory with this name in it. It is also possible to use a
-device name here, see later.
-
-2. Load the kernel. Since it is an ext2/4 filesystem we can do::
-
- => ext2load scsi 0:2 03000000 /boot/vmlinuz-3.13.0-58-generic
-
-The address 30000000 is arbitrary, but there seem to be problems with using
-small addresses (sometimes Linux cannot find the ramdisk). This is 48MB into
-the start of RAM (which is at 0 on x86).
-
-3. Load the ramdisk (to 64MB)::
-
- => ext2load scsi 0:2 04000000 /boot/initrd.img-3.13.0-58-generic
-
-4. Start up the kernel. We need to know the size of the ramdisk, but can use
- a variable for that. U-Boot sets 'filesize' to the size of the last file it
- loaded::
-
- => zboot 03000000 0 04000000 ${filesize}
-
-Type 'help zboot' if you want to see what the arguments are. U-Boot on x86 is
-quite verbose when it boots a kernel. You should see these messages from
-U-Boot::
-
- Valid Boot Flag
- Setup Size = 0x00004400
- Magic signature found
- Using boot protocol version 2.0c
- Linux kernel version 3.13.0-58-generic (buildd at allspice) #97-Ubuntu SMP Wed Jul 8 02:56:15 UTC 2015
- Building boot_params at 0x00090000
- Loading bzImage at address 100000 (5805728 bytes)
- Magic signature found
- Initial RAM disk at linear address 0x04000000, size 19215259 bytes
- Kernel command line: "root=/dev/disk/by-partuuid/965c59ee-1822-4326-90d2-b02446050059 ro"
-
- Starting kernel ...
-
-U-Boot prints out some bootstage timing. This is more useful if you put the
-above commands into a script since then it will be faster::
-
- Timer summary in microseconds:
- Mark Elapsed Stage
- 0 0 reset
- 241,535 241,535 board_init_r
- 2,421,611 2,180,076 id=64
- 2,421,790 179 id=65
- 2,428,215 6,425 main_loop
- 48,860,584 46,432,369 start_kernel
-
- Accumulated time:
- 240,329 ahci
- 1,422,704 vesa display
-
-Now the kernel actually starts (if you want to examine kernel boot up message on
-the serial console, append "console=ttyS0,115200" to the kernel command line)::
-
- [ 0.000000] Initializing cgroup subsys cpuset
- [ 0.000000] Initializing cgroup subsys cpu
- [ 0.000000] Initializing cgroup subsys cpuacct
- [ 0.000000] Linux version 3.13.0-58-generic (buildd at allspice) (gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1) ) #97-Ubuntu SMP Wed Jul 8 02:56:15 UTC 2015 (Ubuntu 3.13.0-58.97-generic 3.13.11-ckt22)
- [ 0.000000] Command line: root=/dev/disk/by-partuuid/965c59ee-1822-4326-90d2-b02446050059 ro console=ttyS0,115200
-
-It continues for a long time. Along the way you will see it pick up your
-ramdisk::
-
- [ 0.000000] RAMDISK: [mem 0x04000000-0x05253fff]
- ...
- [ 0.788540] Trying to unpack rootfs image as initramfs...
- [ 1.540111] Freeing initrd memory: 18768K (ffff880004000000 - ffff880005254000)
- ...
-
-Later it actually starts using it::
-
- Begin: Running /scripts/local-premount ... done.
-
-You should also see your boot disk turn up::
-
- [ 4.357243] scsi 1:0:0:0: Direct-Access ATA ADATA SP310 5.2 PQ: 0 ANSI: 5
- [ 4.366860] sd 1:0:0:0: [sda] 62533296 512-byte logical blocks: (32.0 GB/29.8 GiB)
- [ 4.375677] sd 1:0:0:0: Attached scsi generic sg0 type 0
- [ 4.381859] sd 1:0:0:0: [sda] Write Protect is off
- [ 4.387452] sd 1:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
- [ 4.399535] sda: sda1 sda2 sda3
-
-Linux has found the three partitions (sda1-3). Mercifully it doesn't print out
-the GUIDs. In step 1 above we could have used::
-
- setenv bootargs root=/dev/sda2 ro
-
-instead of the GUID. However if you add another drive to your board the
-numbering may change whereas the GUIDs will not. So if your boot partition
-becomes sdb2, it will still boot. For embedded systems where you just want to
-boot the first disk, you have that option.
-
-The last thing you will see on the console is mention of plymouth (which
-displays the Ubuntu start-up screen) and a lot of 'Starting' messages::
-
- * Starting Mount filesystems on boot [ OK ]
-
-After a pause you should see a login screen on your display and you are done.
-
-If you want to put this in a script you can use something like this::
-
- setenv bootargs root=UUID=b2aaf743-0418-4d90-94cc-3e6108d7d968 ro
- setenv boot zboot 03000000 0 04000000 \${filesize}
- setenv bootcmd "ext2load scsi 0:2 03000000 /boot/vmlinuz-3.13.0-58-generic; ext2load scsi 0:2 04000000 /boot/initrd.img-3.13.0-58-generic; run boot"
- saveenv
-
-The \ is to tell the shell not to evaluate ${filesize} as part of the setenv
-command.
-
-You can also bake this behaviour into your build by hard-coding the
-environment variables if you add this to minnowmax.h:
-
-.. code-block:: c
-
- #undef CONFIG_BOOTCOMMAND
- #define CONFIG_BOOTCOMMAND \
- "ext2load scsi 0:2 03000000 /boot/vmlinuz-3.13.0-58-generic; " \
- "ext2load scsi 0:2 04000000 /boot/initrd.img-3.13.0-58-generic; " \
- "run boot"
-
- #undef CFG_EXTRA_ENV_SETTINGS
- #define CFG_EXTRA_ENV_SETTINGS "boot=zboot 03000000 0 04000000 ${filesize}"
-
-and change CONFIG_BOOTARGS value in configs/minnowmax_defconfig to::
-
- CONFIG_BOOTARGS="root=/dev/sda2 ro"
+Typically U-Boot boots distributions automatically so long an `CONFIG_BOOTSTD`,
+`CONFIG_BOOTSTD_DEFAULTS` and `CONFIG_EFI_LOADER` are enabled. See
+:doc:`manual_boot` for how to do this manually.
Test with SeaBIOS
-----------------
@@ -747,8 +484,5 @@ TODO List
.. _microcode: http://en.wikipedia.org/wiki/Microcode
.. _SFI: http://simplefirmware.org
.. _MP: http://www.intel.com/design/archives/processors/pro/docs/242016.htm
-.. _here: https://en.wikipedia.org/wiki/GUID_Partition_Table
-.. _this: http://events.linuxfoundation.org/sites/events/files/slides/chromeos_and_diy_vboot_0.pdf
-.. _that: http://events.linuxfoundation.org/sites/events/files/slides/elce-2014.pdf
.. _SeaBIOS: http://www.seabios.org/SeaBIOS
.. _ACPI: http://www.acpi.info
--
2.42.0.rc1.204.g551eb34607-goog
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