[coreboot] GRUB 2 is a great payload! (was: GRUB2 is too big as a payload in ThinkPad X201)

[Paul Menzel]

Dear Alexandru,


Am Donnerstag, den 26.03.2015, 11:54 -0700 schrieb Alexandru Gagniuc:
> On Thursday, March 26, 2015 07:53:04 AM Paul Menzel wrote:
> > The file is now 578K big and in CBFS the compressed size is a little
> > over 200 KB.
>
> I never understood how grub2 can do less than seabios but be much larger. OK, 
> you caught me! grub2 can read files off a disk.

On most installations I know, „all that SeaBIOS does“ is to run Option
ROMs (mostly only Video BIOS’s) and then to execute GRUB from somewhere.
Users with a modern operating system don’t need the BIOS legacy stuff it
sets up.

So I don’t know where this GRUB bashing is coming from, but in my
experience GRUB is a great payload and it makes sense to load it
directly and let coreboot run the VGA Option ROM/Video BIOS.

In my tests on with the ASRock E350M1, even though the GRUB payload is
bigger in size, there is no noticeable speed difference between using
SeaBIOS or GRUB as a payload.

Some more great features and modules:

1. GRUB gives you a command line interface. The time-out can be set to 0.
2. Debugging with lspci, lsacpi, setpci, …
3. Instrumentation with boottime, cacheinfo, …
4. Show CBMEM console with `cbmemc`.
5. Show CBMEM time stamps with `coreboot_boottime`.
6. Support for coreboot systems with native graphics support.

And the cherry on top: If you don’t need a functionality, for example in
production after development, most of it is provided through modules. So
customize your build and don’t include the unneeded modules to make the
image even smaller to scrape off the last milliseconds of your boot
time.

So big thank you to the GRUB developers, especially Vladimir
φ-coder/phcoder for their work and support.

Also big thank you to all other payload developers. Especially to Kevin
for working on SeaBIOS, which fulfills its use case awesomely well, and
for being always responsive and helpful.


Thanks,

Paul
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