Quest for a Better Boot-Loader

[torpor]

Its gotta be possible to build a better loadin that'll let me choose a zImage from CF, no?  

Anyone know whats out there that we might use to solve this horrid image-update scene on the sl5500 front?

[Mickeyl]

Your best bet would be using LAB (Linux as Bootloader), which is the next generation boot loader by the handhelds.org crew. Equipped with a JTAG it shouldn't take much to port it... except time and motivation, of course.

[torpor]

why is JTAG required?

don't we just need a FLASH programmer (app) and a zImage/initrd '/boot_dir' setup that fires up a script in linux-single mode, does the menu/flash thing, and reboots?  

I mean, can we not administer, completely, the boot and FLASH ram, from a running linux kernel already?  Wouldn't it be lovely if it were just a matter of /dev/nvram support ...

[Mickeyl]

Uhm... you realize that a PDA bootloader is different from a PC one, right?

On the PC you have a nice BIOS which is always there for you doing the tough hardware initialization work and then hands control to the bootloader which finds everything in place and just has to do a little bit.

On the PDA the bootloader is what initializes the hardware, sets up memory timings, initializes the display etc. It has to do a lot of work - albeit trivial work. It also resides itself in Flash hence the first time when you flash a new one which doesn't work you have a brick.

Without JTAG I wouldn't even think about hacking bootloaders.

[torpor]

yes, i'm familiar with what a bootloader is.  i just don't get why it is a requirement that you have to use the built-in FLASH programmer to flash your own kernel image into the bootable system FLASH RAM from CF?

if it were possible to flash the RAM from a userspace app on a running linux kernel, thus replacing the bootable system image, then we could far better automate the process of replacing linux kernels/initrd images in the base zaurus hardware.

Why does it need a bootloader in the first place, if the flashable RAM is available and can be written to from normal kernel space?  Is there simply no way to flash the RAM from the kernel, i.e. some sorta Sharp'ism on access to onboard Flash RAM?

feel free to indicate which tree i'm not wrongly barking up, I'm new to the zaurus scene ... it just seems to me that with a flash program that can be run in kernel space, we eliminate the need for the C-D trick as the only means of replacing kernel images.  that'd be nice, wouldn't it?

[onerats]

I've been interested in getting JTAG access to my 5500 for a while, partly so that I can poke a little at the bootloader.  The closest thing to a pinout that I've been able to find, though, is a newsgroup post where someone speculates that it might be couched in the contacts next to the battery.  Is there any chance that somebody around here knows the actual pinout or who at Sharp I could contact to get it?  Thanks kindly...

[Mickeyl]

I doubt Sharp will be helpful. Try asking on #openzaurus on irc.freenode.net or #handhelds.org, where skilled zaurus hackers still appear once in a while...