Since testing modules for GRUB by compile/reboot/test/boot/… is time consuming, frustrating – simply not very efficient, there was an utility shipped with the sources called grub-emu that (like the name states) emulates the grub console. But: it was/is not a perfect emulation (stm), no modules are loaded/loadable so every module must be hand-coded-added to the built and… it does not build (like descibed here).
The playground – world:
And thats is okay cause there is another great tool: grub_mkrescue – an image builder that creates floppy/cdrom-images with… grub on it. (and it supports the preloading of modules) Sample:
Gives a GRUB inside qemu with hello.mod already loaded. Fine. Put the lines into the Makefile of the module currently developed (maybe as run-target) and testing becomes a lot easier…
The playground – garden:
Assume you have checked out the (latest) sources of grub2, and now you stay into the source-dir grub-1.98. Your new module (for the firsttime a copy/paste/change of hello/hello.c) goes to grub-1.98/simplemod.
Building a module could be done two ways: the slower one by adding a probate entry in conf/common.mk (simple copy/paste an entry for a given module like hello) – results in building everything again, and again when calling make clean/make… or the good, fast and due to the handcrafted standalone-Makefile ugly one.
No more filling phrases… here is the makefile (to be placed in grub-1.98/simplemod/Makefile):
Okay, on the first time you must create the surrounding grub2-ecosystem (grub-1.98/configure;make;make install). But after that you only need to compile your new module. That is efficient.
Forced by a project@work I had to install GRUB2 in Fedora 14. Here is a simple description of what I have done to got it running:
1. install the new „grand unified bootloader package“ by
Attention: at this time, Fedora uses multislot – GRUB Legacy (0.9x) and GRUB2 could be installed parallel.
2. edit/create the new /boot/grub2/grub.cfg
2.1 My old /boot/grub/grub.conf looks like:
In the snipped above you could see that GRUB2 is allready inserted into the grub.conf of your old GRUB. You could use it for boot into the GRUB command-line.
2.2. create a new grub.cfg
Important: in GRUB Legacy (the old GRUB) the partition-numbering starts with 0. In GRUB2 the numbering starts with 1. So hd0,0 from above becomes hd0,1 eg.
Check/note on witch device/partition your /boot and root is located and witch UUID it has assigned (mount gives you the device /dev/sd…, blkid the associated UUID), sample:
3. Now run
The output is placed into /boot/grub2/grub.cfg.new – do a cat on it and compare the UUID for /boot and root with the ones from above (and maybe compare against your old grub.conf) … and yes, hd0,0 is now hd0,1 .
4. The final step: install the new GRUB on the disc…
First only test that everything is fine… (without writing to MBR assuming the target drive is /dev/sda):
Now lets use the real bullet:
And it works. For me. Now.
GRUB2 offers 1000nds new possibilities (ohh, it has a LUA-shell, there is module-support, submenus, theming, …)
For learning: boot the core.img, load kernel and ramdisk by hand. boot. check console commads ls & cat.
Have a look at:
…compensate the digital dementia by writing things down.