HOWTO: booting Sabayon CoreCD image from a USB flash with Syslinux

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You need +512MB USB flash and .iso of Sabayon CoreCD (here: 5.2 x86).

You get CoreCD installed on one of extended partitions, Sabayon will be working.

It is recommended to backup: HOWTO: separate boot partition with PartedMagic and Clonezilla (dedicated GRUB2 partition)

Install using UNetbootin is a much more preferable way. This HOWTO is about manual install using Syslinux (you have to install Syslinux package during process)

0. Prepare ext4 extended partition to hold CoreCD (here: /dev/sda6). 12GB should be enough.

1. Insert USB flash, run mount:

$ su
# mount

to find where your USB flash is mounted (here: /dev/sdb1 on /media/disk). Unmount it

# umount /media/disk

2. (!) From here and ahead, be careful when writing something like /dev/sdb or /dev/sdb1. Because /dev/sda is your first HDD, and many commands here could make it unbootable. Also, there is a difference in /dev/sdb (USB flash device) and /dev/sdb1 (partition of that device), don't spend time changing this.

Create one primary boot partition

# fdisk -cu /dev/sdb

Useful commands of fdisk are: p - partition table d - delete partition n - create partition a - toogle boot flag w - save and exit

The result:

# fdisk -lu /dev/sdb
Device     Boot  Start  End      Blocks    Id  System
/dev/sdb1  *     2048   8000306  3999129+  83  Linux

Create FAT 32 file system (use FAT 16 for -4GB)

# mkfs.vfat -F 32 /dev/sdb1

3. Install MBR from syslinux on USB flash

# equo install syslinux
# dd if=/usr/share/syslinux/mbr.bin of=/dev/sdb

Mount USB flash

# mkdir -p /mnt/usb
# mount -t vfat /dev/sdb1 /mnt/usb

Mount .iso (here: Sabayon_Linux_CoreCD_5.2_x86.iso)

# mkdir -p /mnt/cdrom
# mount -o loop,ro -t iso9660 /media/sda10/tmp/Sabayon_Linux_CoreCD_5.2_x86.iso /mnt/cdrom

Copy files

# cp -r /mnt/cdrom/* /mnt/usb
# mv /mnt/usb/isolinux/* /mnt/usb
# mv /mnt/usb/isolinux.cfg /mnt/usb/syslinux.cfg
# rm -rf /mnt/usb/isolinux*

Install syslinux on USB flash

# syslinux /dev/sdb1

Test a newly created USB using QEMU

# umount /dev/sdb1
# sync ; echo 3 > /proc/sys/vm/drop_caches ; qemu -usb /dev/sdb1

4. Boot from Sabayon 5.2 CoreCD USB flash.

If it writes something, wait. If it wanting you to select graphical mode, try 800x600 - works for sure. After booting, start installer and follow instructions. Install CoreCD to extended partition (here: /dev/sda6) by choosing a "/" (root) mount point.

(optional) If you followed HOWTO about backup, you already have a separate boot partition (here: /dev/sda1) with GRUB2. So, do not install bootloader to MBR, but install at root.

Reboot to your old Sabayon, open /boot/grub/grub.cfg on CoreCD (!) partition, and find 2 menu entries for CoreCD, they boot from different (hd0,?) and are started at

File: (/boot/grub/grub.cfg)
### BEGIN /etc/grub.d/10_linux ###

Copy them to /etc/grub.d/40_custom. Remove old grub.cfg (make a backup of it!), and generate a new grub.cfg

# rm /media/sda1/boot/grub/grub.cfg
# grub-mkconfig -o /media/sda1/boot/grub/grub.cfg

Test changes using QEMU

# sync ; echo 3 > /proc/sys/vm/drop_caches ; qemu -hda /dev/sda