Blog post about making a GRUB tampoline

config/_default/params.yaml

@@ -69,7 +69,7 @@ address_format: dk
 
 # Site features
 
-highlight: false
+highlight: true
 math: false
 diagram: false
 privacy_pack: false

content/post/bit-magic/index.md

@@ -4,6 +4,7 @@ subtitle: "Tips and trick for embedded C/C++"
 summary: "Tips and trick for embedded C/C++"
 date: 2020-06-13T19:01:19+02:00
 lastmod: 2020-06-13T19:01:19+02:00
+highlight: true
 ---
 
 # Set a bit
@@ -24,7 +25,6 @@ output = input & ~(1 << bit);
 variable &= ~(1 << bit);
 // Multiple bits
 variable &= ~(0b101 << bit);
-
 ```
 
 # Toggle a bit

content/post/grub-trampoline/index.md

@@ -0,0 +1,86 @@
+---
+# Documentation: https://wowchemy.com/docs/managing-content/
+
+title: "GRUB Trampoline"
+subtitle: "Install GRUB on a spare drive"
+summary: "Using a spare drive to act as a trampoline during the boot process."
+date: 2021-05-03T15:28:14+02:00
+lastmod: 2021-05-03T15:28:14+02:00
+highlight: true
+---
+# Background
+
+Due to a BIOS bug in my HP MicroServer I have applied this workaround. The MicroServer Gen8 has a bug that prevents the use of the 5th SATA port as the primary boot device. It will automatically attempt to boot from SATA port 1 if a drive is inserted, then port 2 and so forth. By removing all the fixed drives it is possible to make the system boot from port 5.
+
+It is however possible to boot from the internal USB port or the internal MicroSD slot. So to solve this issue we are going to install GRUB onto a spare MicroSD card or a USB stick. The size or quality of the drive should not matter since we only need it for GRUB to jump to the drive present on the 5th SATA port.
+
+# Steps
+## Format the USB/SD Card
+Find the correct device identifier.
+
+```shell
+lsblk
+```
+
+Clear the drive by writing all zeros to the drive (for good measure)
+
+```shell
+sudo dd if=/dev/zero of=/dev/sdX
+```
+
+Format the disk
+
+```shell
+sudo fdisk /dev/sdX
+```
+
+Fdisk provides a shell where you can enter commands.
+- Set the type to "o" for MSDOS
+- Set the disk to be bootable "a"
+- Make a new primary partition "n" followed by "n" Accept the remaining as default.
+- Use "w" to commit the changes and exit the tool.
+
+Now create a filesystem in the newly created partition.
+
+```shell
+sudo mkfs -t ext2 /dev/sdX1
+```
+
+## Prepare for GRUB install
+Create a mount point
+
+```shell
+mkdir /tmp/mysub
+```
+
+Mount the new parition
+
+```shell
+sudo mount /dev/sdX1 /tmp/myusb
+```
+
+Create a folder named "boot" on the drive
+
+```shell
+sudo mkdir /tmp/myusb/boot
+```
+
+## Install GRUB
+Install GRUB by running the grub-install script
+
+```shell
+sudo grub-install --boot-directory=/tmp/myusb/boot /dev/sdX
+```
+
+Update the GRUB configuration
+
+```shell
+sudo update-grub --output=/tmp/myusb/boot/grub/grub.cfg
+```
+
+## Test
+Finally unmount and reboot 
+```shell
+sudo unmount /tmp/myusb
+sudo reboot
+```