Initramfs/Inspecting: Difference between revisions
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=== Tips and tricks === | === Tips and tricks === | ||
* [[Initramfs development]] has more generalize information about working with initfs. | |||
* [http://www.microhowto.info/howto/copy_a_file_from_one_machine_to_another_using_netcat.html copy files to/from the initramfs with <code>nc</code> while it is running] | * [http://www.microhowto.info/howto/copy_a_file_from_one_machine_to_another_using_netcat.html copy files to/from the initramfs with <code>nc</code> while it is running] | ||
[[Category:Guide]] | [[Category:Guide]] |
Revision as of 10:14, 20 June 2023
This is considered a security hole. Only use it for debugging, and uninstall the debug-shell hook afterwards. |
This page explains how to connect to your device when it has booted to the initramfs by installing the debug-shell hook. This is useful if you want to know more about the boot process, simply inspect the initramfs or if you want to debug why something doesn't work.
It is possible to enable a telnet daemon that gives you a shell this way:
$ pmbootstrap initfs hook_add debug-shell
$ pmbootstrap flasher flash_kernel # or however you flash/boot the kernel
(wait until the device booted up and you are connected to it)
$ telnet 172.16.42.1
Trying 172.16.42.1...
Connected to 172.16.42.1.
Escape character is '^]'.
Type 'pmos_continue_boot' to continue booting:
# echo "hello world"
hello world
# pmos_continue_boot
Connection closed by foreign host.
If the telnet command does not work out of the box, read connect via USB Networking in the Initramfs.
Enable initramfs-extra
To enable functionality from initramfs-extra, run the following commands in the telnet shell:
# . /etc/deviceinfo
# . /init_functions.sh
# mount_boot_partition /boot
Mount boot partition (/dev/dm-0)
# extract_initramfs_extra /boot/initramfs-extra
Extract /boot/initramfs-extra
24128 blocks
In general, while inspecting the initramfs, you can execute commands in order listed in postmarketos-initramfs/init.sh, starting with the line mount_boot_partition /boot
and below (everything above it was already executed before entering debug-shell).
Additional programs
After installing the debug-shell
initramfs hook, the evtest
, fftest
and fbdebug
programs are available in the initramfs (#1358).
Deleting the debug shell
pmbootstrap initfs hook_del debug-shell
Tips and tricks
- Initramfs development has more generalize information about working with initfs.
- copy files to/from the initramfs with
nc
while it is running