Kernel Adventure

Tuesday, 7 July 2020

vm - Centos - Boot into latest Kernel

sudo grub2-set-default 0
sudo grub2-mkconfig -o /boot/grub2/grub.cfg
sudo reboot

Monday, 6 July 2020

vm - Centos Shared Folder

Launch VMware -> Virtual Machine Settings -> Hardware

Enable only one CD/DVD(IDE) -> Tick "Connect at power on" -> Use a physical drive: Auto Detect

Uninstall open-vm-tools

https://kb.vmware.com/s/article/1013096

rpm -e open-vm-tools

Manual install VMwave-tools

https://kb.vmware.com/s/article/1018414

To create a mount point, run:

mkdir /mnt/cdrom
To mount the CDROM, run:

mount /dev/cdrom /mnt/cdrom
To copy the Compiler gzip tar file to a temporary local directory, run:

cp /mnt/cdrom/VMwareTools-version.tar.gz /tmp/

Where version is the VMware Tools package version.
To determine the version of VMware tools, run:

ls /mnt/cdrom

You see output similar to:

# VMwareTools-5.0.0-12124.tar.gz
To change to the tmp directory and extract the contents of the tar file into a new directory called vmware-tools-distrib, run:

cd /tmp
tar -zxvf VMwareTools-version.tar.gz
To change directory to vmware-tools-distrib and run the vmware-install.pl PERL script to install VMware Tools, run:

cd vmware-tools-distrib
./vmware-install.pl

Sunday, 3 May 2020

Walk-Through

SECTION

SETUP

show hide

LINUX BOX	show hide
QEMU	show hide

what is the shell?
ls -l /bin/sh
/bin/sh -> dash
/bin/sh -> bash
/bin/sh -> busybox

Friday, 1 May 2020

Walk-Through

SECTION

SETUP

PACKAGE	show hide
GIT	show hide
SOURCE	show hide
SYSTEM	show hide
CLEAN	show hide
CONFIG	show hide
MODULE	show hide
MAKE	show hide
RUN	show hide
TEST	show hide
NEXT	show hide

LINUX BOX	show hide
QEMU	show hide

(INSTALL) PACKAGE

$ apt-get update
$ apt-get upgrade
$ sudo apt install apt-file
$ sudo apt-file update
$ sudo apt-get install install-info
$ sudo apt install vim libncurses5-dev gcc make git git-all git-email gitk esmtp mutt exuberant-ctags libssl-dev bison flex libelf-dev bc build-essential kernel-package fakeroot ccache ncurses-dev alien cscope meld gitk libssl1.1 codespell python-ply qemu qemu-system gdb
$ pip install gitpython

(SETUP) GIT

$ git config --global user.name "John Doe"
$ git config --global user.email johndoe@gmail.com

Email:

Create Google App Passwords

$ vim ~/.muttrc

Example:

set realname = "John Doe"
set from = "johndoe@gmail.com"
set use_from = yes
set envelope_from = yes
set edit_headers=yes

set smtp_url = "smtps://johndoe@gmail.com@smtp.gmail.com:465/"
set smtp_pass = {SMPT_APP_PASSWORD}
set imap_user = "johndoe@gmail.com"
set imap_pass = {IMAP_APP_PASSWORD}
set imap_keepalive = 900
set timeout = 10
set ssl_force_tls = yes
set ssl_starttls = yes

bind index G imap-fetch-mail
set folder = "imaps://imap.gmail.com:993"
set spoolfile = "imaps://imap.gmail.com/INBOX"
set header_cache=~/.mutt/cache/headers
set message_cachedir=~/.mutt/cache/bodies
set certificate_file=~/.mutt/certificates
set record = ""
set postponed = "imaps://imap.gmail.com/[Gmail]/Draft"
set editor = "vim"
set charset = "utf-8"

Create Yahoo App Passwords

$ vim ~/.muttrc

Example:

set realname = "John Doe"
set from = "johndoe@gmail.com"
set use_from = yes
set envelope_from = yes
set edit_headers=yes

set smtp_url = "smtps://johndoe@gmail.com@smtp.gmail.com:465/"
set smtp_pass = {SMPT_APP_PASSWORD}
set imap_user = "johndoe@gmail.com"
set imap_pass = {IMAP_APP_PASSWORD}
set imap_keepalive = 900
set timeout = 10
set ssl_force_tls = yes
set ssl_starttls = yes

set folder = "imaps://export.imap.mail.yahoo.com:993"
set spoolfile="imaps://imap.mail.yahoo.com/INBOX"
set header_cache=~/.mutt/cache/headers
set message_cachedir=~/.mutt/cache/bodies
set certificate_file=~/.mutt/certificates
set record="imaps://imap.mail.yahoo.com/Sent"
set postponed="imaps://imap.mail.yahoo.com/Drafts"
set editor = "vim"
set charset = "utf-8"

$ mutt

Say "no" to creating an inbox for now. Type 'm' to create a new message. Specify your own email address (or a secondary email) to send the test message to. Set the Subject however you want to. Type a message in the body, and then save and quit. Hit 'y' to send the message, hit 'e' to edit the message again, or hit 'q' to abort sending the message.

Look in your email to double check you received a message. If you send the email to yourself, for some mail services like gmail, the message will not show up in your inbox, and you will have to look in your Sent Mail folder.

(INSTALL) SOURCE (CODE)

$ git clone -b staging-testing git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
$ git tag -l | less # list out the kernel versions
$ git checkout -b stable tag # Where tag is the latest vX.Y.Z tag you found.
$ git branch test # create branch named test, don't mess up the master branch (tree)
$ git checkout test # select test branch
$ git branch # check if currently at test branch

(FILE)SYSTEM

created rootfs.ext4 with buildroot

$ git clone git://git.buildroot.net/buildroot

$ cd buildroot

$ make menuconfig

Target Options → Target Architecture (x86_64) → (X) x86_64 # run it on x86_64 virtualized system with qemu.

Filesystem images → [*] ext2/3/4 root file system → ext2/3/4 variant (ext4) → (X) ext4 # ext4 file system to be mounted as default file system

$ make -j8 - Build ‘buildroot’ project

The rootfs.ext4 has been created

CLEAN( UP)

Cleaning is done on three levels.

$ make clean # Delete most generated files to build external modules
$ make mrproper # Delete the current configuration and all generated files
$ make distclean # Remove editor backup files, patch leftover files, etc

Delete old official kernels from boot loader

$ dpkg -l | grep linux-image- # list out (previous) installed kernels

......
rc linux-image-4.15.0-96-generic 4.15.0-96.97 amd64 Signed kernel image generic
rc linux-image-4.15.0-99-generic 4.15.0-99.100 amd64 Signed kernel image generic
ii linux-image-5.0.0-32-generic 5.0.0-32.34~18.04.2 amd64 Signed kernel image generic
rc linux-image-5.0.0-37-generic 5.0.0-37.40~18.04.1 amd64 Signed kernel image generic
......

$ sudo apt-get autoremove linux-image-5.3.0-51-generic # autoremove desired kernel
reboot
$ sudo apt-get autoclean & apt full-upgrade & apt-get dist-upgrade # upgrade everything again

Delete Custom Compiled Kernel from boot loader

$ sudo locate "*5.5.0-rc6*" | sudo xargs -p -ixxx rm -f 'xxx' # identify the files of kernels

Remove the following files:

$ sudo rm /boot/vmlinuz-5.5.0-rc6+
$ sudo rm /boot/initrd-5.5.0-rc6+
$ sudo rm /boot/System-5.5.0-rc6+
$ sudo rm /boot/config-5.5.0-rc6+
$ sudo rm /lib/modules-5.5.0-rc6+

and Finally,

$ sudo update-grub # boot loader as well

NOTE:

"E: gconf2: dependency problems - leaving triggers unprocessed"

try:

$ sudo dpkg --configure -a

CONFIG

$ cp /boot/config-`uname -r`* .config # [TRY THIS 1ST] duplicating your current config

$ make localmodconfig # utilized existing .config with modules installed

$ make menuconfig # Text-based with colored menus and radiolists.

$ make defconfig # This option creates a config file that uses default settings based on the current system's architecture.

$ make ${PLATFORM}_defconfig - Creates a config file using values from arch/$ARCH/configs/${PLATFORM}_defconfig.

$ make ARCH=x86_64 x86_64_defconfig # pick current kernel setting as base

$ make ARCH=x86_64 menuconfig # add debugging ability in TUI
Kernel hacking --->
Compile-time checks and compiler options --->
[*] Compile the kernel with debug info
[*] Provide GDB scripts for kernel debugging (New)
[ ] Reduce debugging information

(MODIFY )MODULE

$ lsmod # list out modules says, want to modify e1000e

says, want to modify e1000

......
e1000e 123456 0
......

THEN EITHER,
$ git grep e1000e -- '*Makefile' # search the module path
OR
$ modinfo e1000e # find module path

filename: /lib/modules/X.X.X-XX-generic/kernel/drivers/net/ethernet/intel/e1000e/e1000e.ko
version: 3.2.6-k
license: GPL v2
description: Intel(R) PRO/1000 Network Driver
......

so, the path is drivers/net/ethernet/intel/e1000e
THEN,
$ vim drivers/net/ethernet/intel/e1000e/*.c # open all c files & find probe function

so, the path is drivers/net/ethernet/intel/e1000
THEN,
$ vim drivers/net/ethernet/intel/e1000/*.c # open all c files & find probe function

add a line to printk() to probe function for TESTing,

NOTE: ":n" to next file, ":N" return to last file, "/probe" to search keyword "probe"

struct e1000_hw *hw; # search for probe function by "/probe" in vi
.....
static int e1000_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
{
struct net_device *netdev;
struct e1000_adapter *adapter;
struct e1000_hw *hw;

printk(KERN_DEBUG "DEBUG: Passed %s %d \n",__FUNCTION__,__LINE__);
const struct e1000_info *ei = e1000_info_tbl[ent->driver_data];
.....

MAKE (INSTALL)

$ make M=drivers/usb/serial -j8 # Build only a portion of the kernel with 4 core CPU
$ lscpu # check how many core the pc has
$ make -j8 # Build entire kernell with 4 core CPU
$ sudo make modules_install # Install the Linux kernel modules
$ sudo make install # sudo make install

Ubuntu (Default boot into latest kernel):
$ sudo update-grub2
Centos (Default boot into last kernel):
$ sudo grub2-set-default 0 # set to latest kernel
$ sudo grub2-mkconfig -o /boot/grub2/grub.cfg

$ sudo reboot

RUN

Reboot
Hold "Shift" at startup
Select & Boot with installed kernel

without debugger:

$ qemu-system-x86_64 -kernel arch/x86/boot/bzImage \
-boot c -m 2049M -hda ../buildroot/output/images/rootfs.ext4 \
-append "root=/dev/sda rw console=ttyS0,115200 acpi=off nokaslr" \
-serial stdio -display none

with debugger:

$ qemu-system-x86_64 -s -kernel arch/x86/boot/bzImage \
-boot c -m 2049M -hda ../buildroot/output/images/rootfs.ext2 \
-append "root=/dev/sda rw console=ttyS0,115200 acpi=off nokaslr" \
-serial stdio -display none

Login as root (id = root, no passowrd)

# mkdir home # home directory not created by default
# adduser newuser # create normal user account
# exit
login as newuser

TEST

$ dmesg | less
type:

/DEBUG: Passed

[ 2.093005] [ 2.114507] DEBUG: Passed e1000_probe 926 c

WHAT'S NEXT

[linux] remove old kernel

Remove Old Kernel

dpkg -l | grep linux-image-

rc  linux-image-4.15.0-74-generic                      4.15.0-74.84                                       amd64        Signed kernel image generic
rc  linux-image-4.15.0-76-generic                      4.15.0-76.86                                       amd64        Signed kernel image generic
rc  linux-image-4.15.0-88-generic                      4.15.0-88.88                                       amd64        Signed kernel image generic
rc  linux-image-4.15.0-91-generic                      4.15.0-91.92                                       amd64        Signed kernel image generic
rc  linux-image-4.15.0-96-generic                      4.15.0-96.97                                       amd64        Signed kernel image generic
rc  linux-image-4.15.0-99-generic                      4.15.0-99.100                                      amd64        Signed kernel image generic
ii  linux-image-5.0.0-32-generic                       5.0.0-32.34~18.04.2                                amd64        Signed kernel image generic
rc  linux-image-5.0.0-37-generic                       5.0.0-37.40~18.04.1                                amd64        Signed kernel image generic
rc  linux-image-5.3.0-26-generic                       5.3.0-26.28~18.04.1                                amd64        Signed kernel image generic
rc  linux-image-5.3.0-28-generic                       5.3.0-28.30~18.04.1                                amd64        Signed kernel image generic
rc  linux-image-5.3.0-40-generic                       5.3.0-40.32~18.04.1                                amd64        Signed kernel image generic
rc  linux-image-5.3.0-42-generic                       5.3.0-42.34~18.04.1                                amd64        Signed kernel image generic
rc  linux-image-5.3.0-45-generic                       5.3.0-45.37~18.04.1                                amd64        Signed kernel image generic
ii  linux-image-5.3.0-46-generic                       5.3.0-46.38~18.04.1                                amd64        Signed kernel image generic
ii  linux-image-5.3.0-51-generic                       5.3.0-51.44~18.04.2                                amd64        Signed kernel image generic
ii  linux-image-generic-hwe-18.04                      5.3.0.51.104                                       amd64        Generic Linux kernel image



Column (desired action):
u = Unknown
i = Install
h = Hold
r = Remove
p = Purge



Column (package status):
n = Not-installed
c = Config-files
H = Half-installed
U = Unpacked
F = Half-configured
W = Triggers-awaiting
t = Triggers-pending
i = Installed

sudo apt-get autoremove linux-image-5.3.0-51-generic
Reboot
sudo apt-get autoremovesudo apt-get autocleansudo apt full-upgradesudo apt-get dist-upgrade

sudo update-grub

Remove Custom Compiled Kernel

uname -srm

locate "*5.16.0-rc3*" | sudo xargs -ixxx rm -rf 'xxx'

sudo update-grub

Thursday, 23 January 2020

mount drive in VirtualBox linux

prerequisites

Assume local Shared Folder: sfolder; VM mount: /home/<user>/vfolder

Insert Guest Additions CD Image
sudo apt-get install virtualbox-guest-dkms
sudo apt-get install virtualbox-guest-utils

cd /opt/VBoxGuestAdditions-*/init

sudo ./vboxadd setup

touch ~/vfolder
chmod 777 ~/vfolder

sudo vim /etc/modules
=>
vboxsf

mount the local Shared Folder

sudo vim /etc/fstab
=>
sfolder /home/<user>/vfolder vboxsf defaults 0 0

mount the network Windows Shared Folder

cifs

//[localip]/[folder] /mnt/[localfolder] cifs credentials=/XXXX/.credentials,vers=3.0,iocharset=utf8,file_mode=0777,dir_mode=0777,uid=[USERNAME],gid=[USERNAME],nofail,sec=ntlmssp 0 0

Tuesday, 21 January 2020

[linux] changes

Duplicating your current config

cp /boot/config-`uname -r`* .config

Making the default config

make defconfig

Change a module

vim drivers/net/ethernet/intel/e1000e/netdev.c

......

struct e1000_hw *hw;

printk(KERN_ALERT "DEBUG: Passed %s %d \n",__FUNCTION__,__LINE__);

Compile a kernel

make M=drivers/usb/serial -j8 # Build only a portion of the kernel with 4 core CPU
lscpu # check how many core the pc has
make -j8 # Build entire kernell with 4 core CPU

make localmodconfig

Build kernel

make -JX

Run on QEMU

qemu-system-x86_64 -no-kvm -kernel arch/x86/boot/bzImage -hda /dev/zero -append "root=/dev/zero console=ttyS0" -serial stdio -display none

Install a kernel

sudo make install

Build a module

make modules SUBDIRS=drivers/the_module_directory

Install a module

sudo make modules_install SUBDIRS=drivers/the_module_directory

OR (if the driver installed as a module, just recompile it)

make drivers/usb/host/xhci-hcd.ko

Reload the module

sudo rmmod xhci-hcd && sudo insmod drivers/usb/host/xhci-hcd.ko

Remove kernel from boot

sudo rm -rf /lib/modules/3.3.7*

sudo rm -rf /usr/lib/modules/$(uname -r)

/boot

/lib/modules

update-grub

Remove kernel from grab

Now I understand the difference between an updated kernel and install and compile a kernel. I compiled all this kernel and the solution to delete was:

I went to nautilus as root sudo nautilus and just deleted:

/boot/vmlinuz "kernel I want to delete"

/boot/initrd "kernel I want to delete"

/boot/System "kernel I want to delete"

/boot/config "kernel I want to delete"

/lib/modules "kernel I want to delete"

and updated the grub sudo update-grub2

OR

locate *5.5.0-rc6*
sudo rm /lib/modules/5.5.0-rc6+
sudo rm -rf /lib/modules/5.5.0-rc6+

Loadable Kernel Modules

list modules

lsmod

......

e1000e 249856 0

......

module info

modinfo e1000e

......

name: e1000e

vermagic: 5.3.0-26-generic SMP mod_unload

signat: PKCS#7

signer:

sig_key:

sig_hashalgo: md4

parm: debug:Debug level (0=none,...,16=all) (int)

parm: copybreak:Maximum size of packet that is copied to a new buffer on receive (uint)

parm: TxIntDelay:Transmit Interrupt Delay (array of int)

parm: TxAbsIntDelay:Transmit Absolute Interrupt Delay (array of int)

parm: RxIntDelay:Receive Interrupt Delay (array of int)

parm: RxAbsIntDelay:Receive Absolute Interrupt Delay (array of int)

parm: InterruptThrottleRate:Interrupt Throttling Rate (array of int)

parm: IntMode:Interrupt Mode (array of int)

parm: SmartPowerDownEnable:Enable PHY smart power down (array of int)

parm: KumeranLockLoss:Enable Kumeran lock loss workaround (array of int)

parm: WriteProtectNVM:Write-protect NVM [WARNING: disabling this can lead to corrupted NVM] (array of int)

parm: CrcStripping:Enable CRC Stripping, disable if your BMC needs the CRC (array of int)

search the module

git grep e1000e -- '*Makefile'

load module at boot

normally

sudo vim /etc/modules

......

e1000e

with params

sudo vim /etc/modprobe.d/e1000e.conf

option e1000e debug=11

Tuesday, 7 July 2020

Monday, 6 July 2020

Sunday, 3 May 2020

Walk-Through

Friday, 1 May 2020

Walk-Through

(INSTALL) PACKAGE

(SETUP) GIT

(INSTALL) SOURCE (CODE)

(FILE)SYSTEM

CLEAN( UP)

CONFIG

(MODIFY )MODULE

MAKE (INSTALL)

RUN

TEST

WHAT'S NEXT

Thursday, 30 April 2020

Thursday, 23 January 2020

prerequisites

mount the local Shared Folder

mount the network Windows Shared Folder

Tuesday, 21 January 2020

Duplicating your current config

cp /boot/config-`uname -r`* .config

Change a module

Compile a kernel

Build kernel

Install a kernel

sudo make install

Build a module

Install a module

Reload the module

Remove kernel from boot

Loadable Kernel Modules

list modules

module info

search the module

load module at boot

normally

with params