Joshua Wise <[EMAIL PROTECTED]> writes: > On Thursday 18 December 2003 7:36 pm, Eric W. Biederman wrote: > > Brainstorming earlier today I think I have found a way to use > > an linux kernel for the boot loader and to implement pcbios > > compatibility without too much cost. The idea is to use > > a uclinux kernel. And implement a ``user space'' aplication > > that is a user space shim that makes kernel calls. > > The way I implement my bootloader on ARM is like this: > > 1) First stage assembly loader sets up serial and DRAM. > 2) First stage loader probes RAM, and sets up tagged list.
Roughly what LinuxBIOS does. > 3) First stage jumps into zImage of special LAB (Linux As Bootldr) kernel. > (currently just a 2.6.0 kernel from handhelds.org that has CONFIG_LAB > defined.) > 4) LAB kernel boots up until it gets ready to jump into init. > 5) #ifdef'ed code takes over and calls a LAB main function which does all > sorts of cool stuff including giving the user a CLI if requested (usually by > holding the iPAQ's joypad down), or autobooting (running a predefined > mkdir/mount/armboot sequence.) > > Conceivably you could write a subapp for the CLI that does what you want, and > put it in the autoboot script. Somehow I could write a subapp that would make linux look like a normal pcbios, but I can be surprised. > LAB for ARM's zImage is currently ~509kbytes for those who care. (We must keep > it below 512KB.) Ouch! My x86 images are below that, at least before decompression. > > There are a few nasty details to work out like how to handle > > services that are expected to work in vm86 mode. But I'm > > not certain I care. > I've tinkered with writing an OS, but I still don't know too much about the > x86 architecture, so I couldn't help there. Sorry. > > > Other thoughts? > Check out my LAB code, see what you think. It's in handhelds.org anoncvs, > module linux/kernel26. Relevant crap is in bootldr/, drivers/bootldr/, and > arch/arm/boot/. I probably will. Doing that stuff inside the kernel does not really feel proper to me. I already have an x86 kernel that can load another kernel from user space. I'm just trying to find a good long term architecture for using the kernel as a bootloader. > > After I come back from my christmas vacation I am going to have to try > > it and see how will it will actually work. > Take care, have a nice vacation. Thanks. Eric _______________________________________________ Linuxbios mailing list [EMAIL PROTECTED] http://www.clustermatic.org/mailman/listinfo/linuxbios
