Success! Jnode 0.2.5 booting from Harddisk and EXT2

After a lot of trial and error, and far too many false starts, I have finally successfully built a Jnode 0.2.5 PC which boots and runs from an EXT2-formatted filesystem mounted read/wrote from the harddisk, without CDROM or USB support.

And I still have 14GB of free disk space to use for builds and testing.

Details after the break...

--- Hardware ---
I assembled a bunch of spare parts laying around into a testbed machine.

CPU: 2 x Pentium III 500MHz
Motherboard: SuperMicro P6DGU
RAM: 2 x 256MB and 2 x 128MB - 768 MB total
Video: STB Systems/NVidia Riva TNT 1.10 16MB
Network: Intel EtherExpress Pro 100
Hard disk: Seagate ST315320 IDE 15GB
PS2 Keyboard, Logitech wheel mouse, and XVGA monitor to round things out.

--- ! USB ---
The BIOS version in the SuperMicro motherboard I have doesn't support USB booting.
If it did, this whole thing would have probably been MUCH easier, and was the first thing I tried.
No luck, so I had to roll the filesystem the hard way.
Plus, I learned a lot more and got the gigs and gigs of writable space to experiment with that I wanted anyway.

--- The Roadmap ---
1. Download Jnode 0.2.5 ISO and sources to a workdir.

2. Run build.sh x86 cd-x86-lite javadoc check-plugins

This gave me the all/build/x86/32bits/bootdisk pieces I needed.

To build the hardware, I went through all/build/descriptors/*.xml to find the PCI ID numbers for each device supported.
From a Fedora rescue CD, I swapped parts around and used lspci to identify the PCI IDs for various spares here.
Once I had a video card and NIC with a supported PCI ID, I test booted from the Jnode ISO to make sure things worked as expected.

--- Boot Disk? ---
Once I was certain the hardware could at least minimimally do the job, I thought it would be a short step to a bootable Jnode hard drive.
Alas, the boot drive turned out to be the biggest stumbling block, as you can see from my posts a couple of months ago trying this with Jnode 0.2.4.
Over the past few days, I found some time and inclination to return to this part and finally got things working.

--- Filesystem Flavor? ---
First, I have no good experience with FAT32/VFAT/YAFAT and all of the bewildering partition types, Windows versions necessary, etc.
I also couldn't make heads or tails out of how to build a FAT filesystem that would be usable for Jnode, under Fedora.
So, a VFAT/FAT32 or whatever really wasn't an option for me.

As a long-time Unix/Linux victim, EXT2 seemed the way to go.

But, for the life of me, I could NOT get Jnode to recognize most EXT2 disks I built.
That's where I left everything under Jnode 0.2.4.
I could boot and run from ISO and in VMware, but that's all.
If Jnode recognized the EXT2 filesystem, it would complain about the LARGE_FILES filesystem option, and mount the filesystem as read-only.
Then my day job exploded in my face and I haven't had time or energy to even think about a fun project like Jnode.

--- Return To Bootlandia ---
Things at work have wound down enough to return to looking at this.
As I got back into Jnode and picked back up where I left off months ago, I decided to start over with a fresh Jnode 0.2.5 build directory and everything, and work through the problem.

Once I was sure my system would build Jnode 0.2.5, it was time to plan the attack.
I went into the JNode-FS source and mapped out which exact EXT2 options were supported.
The fs/src/fs/org/jnode/fs/ext2/ directory had everything I needed.

Specifically, SuperBlock.java, Inode.Java and Ext2Constants.java lead me to the following specific EXT2 configuration as "supported":
4096 bytes-per-inode, 5% reserved blocks ratio, sparse superblocks option, no filetype option, no large_files option, max mount_count 255, max mount_interval 365 days, revision 1, OS value 42, and inode size of 128.

Normally, the Linux commands to create that exact filesystem would be:
# mkfs.ext2 -i 4096 -L JNODE025 -m 5 -O sparse_super -r 1 -o 42 -I 128 /dev/hdX
# tune2fs -c 255 -i 365 /dev/hdX

And it should be just that (easy? if you like Linux I guess), except e2fstools doesn't allow control over the large_files option, that I can find.
Every EXT2 filesystem I built from a e2fstools on a Fedora rescue or live CD had that LARGE_FILES option.
I could find no mkfs.ext2 or tune2fs options to make it stop.
The only way I could find to avoid the large_files bits was as ridiculous as rebuilding e2fsprogs or the entire kernel?!?
I just said no to that. I want to mess with Java, not stir around with a load of C/C++ stuff, and kernel rebuilds are fun, but not to simply remove a superblock option.

The conclusion?
Don't use a modern Linux/e2fs tools to build an EXT2 filesystem for Jnode.

--- The Way Around ---
Stepping into the Wayback machine, I pulled out a RedHat 5.2 CD set. But, that wanted to build a rescue floppy.
Sherman, that was TOO far back.

Setting the Wayback Machine forward a bit to a RedHat 6.2 CD set, booted to rescue mode from that, performed some device-foo to get the hard drive recognized as a valid device, built a single Linux 0x83 type partition on the drive, set it active, and laid down an EXT2 filesystem into it using the exact two commands I listed above. Unfortunately, RH6.2 tune2fs did not support the -l "list superblock" info to confirm that sparse_files was the only option set.

So, I set the Wayback Machine forward a bit more, booted from a Fedora Core 5 CDROM into rescue mode and enabled networking.
The FC5-supplied tune2fs showed that the filesystem options were correct, so I went ahead and ran the GRUB pieces from FC5.
I also used scp from the FC5 rescue mode to copy over the all/build/x86/32bits/bootdisk/ contents into the drive root.
Finally, I scp over some fun stuff to try out, like a simple web browser class, an e-mailer class, some desktop toys, and more to mess with if I got it working.

--- SUCCESS ---
Once I had the filesystem in place, I unmounted the Jnode disk, removed the Jnode live CD, and let it rip.

I oopsed the GRUB setup somehow, so the test boot doesn't have its menu.
I think I should have copied the menu.lst first, before doing the grub-install.
Ah well, easily fixed in the next build.
Oh wait, its FEDORA's GRUB, which wants /boot/grub/grub.conf instead of /boot/grub/menu.lst maybe that's it.

A simple "configfile /boot/grub/menu.lst" at the grub> prompt gave me the menu I wanted.
Simply wait, or press enter on Jnode (default) starts it booting.

I wait, and within a few seconds, I see:
.INFO [Ext2FileSystem]: hda0 mounting fs r/w
INFO [FileSystemMounter]: Mounted EXT2 on /devices/hda0

I am so relieved.
Once the Jshell comes up (34 seconds total boot time on that old CPU), I run gc then cd into /devices/hda0 to check it out.
Looking good... now to start messing with it!

I know its not news about earth-shattering new features or anything, but I am pretty geeked to finally get this setup and booting the way I wanted.

--- Next Steps ---
I want to build Jnode 0.2.5 using IcedTea on Fedora 8, rather than JDK7 EA B24 (which I use for work reasons).

I also want to rebuild everything from scratch and document the exact steps better, now that I know how to get this working, generally.

While I am at it, I would like to come up with a GRUB and e2fsprogs kit to build and maintain these filesystems a bit simpler than booting from stacks of various RedHat and Fedora rescue disks.

And, I would like to come up with a "System Compatibility Check" to run from the GRUB menu that lists the PCI IDs and whether or not they are supported.

--- P.S. ---
Someone, anyone, please feel free to add the Linux commands to correctly build a Jnode-friendly FAT32/VFAT/other filesystem?