rhel7 boot option tips

static ip
format=ip:method:gw:netmask:hostname:ifname:none
ip=IP_ADDR::192.168.0.1:255.255.255.0:hostname:eth0:none

leave ifname to empty if you cannot predict the IFname. add net.ifnames=0 to boot option to disable device name inquiry from BIOS. (biosdevname=0)

inst.stage=nfs:nfsvers=3:nfs:192.168.0.1:/yum/rhel7.2
inst.repo=nfs:nfsvers=3:nfs:192.168.0.1:/yum/rhel7.2
inst.ks=http://192.168.0.1/yum/rhel7.2


pxelinux.0 4.0.4 supports image fetching through http.


inst.stage2=http://10.5.15.10/repo/rhel7.5_ceph3.0 text inst.sshd console=tty0 console=ttyS1,115200n8 vlan=vlan1214:enp61s0f0 ksdevice=vlan1214 ip=10.102.14.53::10.102.14.1:255.255.255.0::vlan1214:none

extract centos7/rhel7 initramfs

# /usr/lib/dracut/skipcpio /boot/initramfs-3.10.0-327.18.2.el7.x86_64.img | gunzip -c | cpio -dcim
# /usr/lib/dracut/skipcpio /boot/initramfs-3.10.0-327.18.2.el7.x86_64.img | zcat | cpio -idmvc
extract initrd.img resided in isolinux folder.
xz -dc initrd.img|cpio -idmv

http://www.constantstream.com/2016/06/16/extract-initramfs-on-rhelcentos-7/

repack:
xz -z -9 -C crc32 -F xz 1
-C for --check
-F for --format

find . |cpio -c -o |xz -z -9 -C crc32 -F xz > /dev/shm/test.img

network interface name tweaking

apply following options for installation process.
net.ifnames=0 biosdevname=0

process bonding to CPU

list process which are run on specific processor.

ps -ax -o pid,cpuid,args,user|awk '$2 == 3{print $0}'

ps -ax -o pid,cpuid,args,user|awk '$3 == "/usr/bin/ceph-osd" {print $0}'

ref: https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Resource_Management_Guide/sec-cpuset.html
https://codywu2010.wordpress.com/2015/09/27/cpuset-by-example/

ses raw command example

sg_ses -c -p dm /dev/sgxx -d 00,00,00,00,0f,00,00,00,00,00,00,00,00,00,00,00

for sending download microcode mode 0x0f

sg_ses -p 0x2 -c -d 00,00,00,00,00,00,00,00,80,80,40,00,80,80,40,00,80,80,40,20 /dev/bsg/0:0:89:0  -vvv
sg_senddiag -pf -r 2,0,0,c,0,0,0,0,0,0,0,0,80,80,40,0 -vvv /dev/sg0
sg_ses  --index=_23,00 --set=2:1:1=1 /dev/sg0 -vv (in this format, _23 refers to type code 0x17 - Array device slot. for the set option, it refers to byte 2 bit 1 right shift 1-1 bit)


ex:
data was 80 80 42 00
set=2:1:3=1
changed to 80 80 40 80

trick: no need to append page header in raw format. to check header type code. sg_ses -e , to check supported diag command : sg_ses -ee

scsi_wait_scan not found

kernel 3.10.x已移除scsi_wait_scan module但預設的系統卻會包含此module的probe

進而造成kernel panic issue

simply remove scsi_wait_scan module probe from init to get it fixed. 

build iso image

 mkisofs  -P "Kido Yen" -V "Redhat 6.x/7.x boot disk" -o ../file.iso -b isolinux.bin -c boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -R -J -v -T ./


with efi support
mkisofs -b isolinux/isolinux.bin -c boot.cat -no-emul-boot  -boot-load-size 4 -boot-info-table -eltorito-alt-boot -e images/efiboot.img -no-emul-boot -R -J