-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 28/05/10 00:00, Andrew Dennison wrote: [...] > I can describe it in general terms. [...snip...]
That's very interesting; it's nice to hear how this sort of thing works in the real world. ARM, I presume? If I may ask, what made you decide to use Prex and not a more established OS like ECOS or FreeRTOS? [...] > I would like to add features to Prex like tickless operation, Futexes > and a better model for task / server memory operations as a few > examples but it would be nice to have a proper collaborative > development model so I'm not effectively maintaining a fork that has > to be rebased onto the moving target of the "official" tarballs that > come out occasionally. Yes, it's a pity. I suspect Kohsuke Ohtani simply doesn't have time/inclination to be a source herder. As you know, it's a thankless and surprisingly complicated job. Incidentally, I'm making decent progress with the Cybiko port. I managed to persuade the build system to produce a linked-together image consisting of kernel and bootup tasks, which lets me run them all out of flash. I've got it booting up into 'user' mode and trying to load /boot/init. Currently that's failing because I haven't done an H8300S elf relocator yet. But it's running multiple processes and threads, interrupts are working, the timer is running --- no preemption or exceptions yet, but that's not bad for under a week's work. The biggest hurdles in the code were getting my head around the rather strange and undocumented way user/kernel stacks work (it's not obvious it's necessary to remember what your kernel stack is when switching to user mode, and switching back to it on a syscall or interrupt). And syscall_ret has nothing to do with returning from system calls. However, the really nasty bits were (a) figuring out how to drive ld to link my image together in really non-standard ways and (b) figuring out the build system. Prex's Make-based build system is a paragon of excellence compared to most Make build systems, but it's still a Make build system and therefore inscrutable and horribly inflexible, and I had to rewrite big chunks of it to support my kernel XIP stuff. It just so happens that I have a build tool of my own <plug> http://primemover.sf.net </plug> that is ideally suited for this sort of project. Would anyone be interested in a new, better build system? - -- ┌─── ｄｇ＠ｃｏｗｌａｒｋ．ｃｏｍ ───── http://www.cowlark.com ───── │ │ life←{ ↑1 ⍵∨.^3 4=+/,¯1 0 1∘.⊖¯1 0 1∘.⌽⊂⍵ } │ --- Conway's Game Of Life, in one line of APL -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkwFQqQACgkQf9E0noFvlzjSyACfUODseY2hCx2kLYBE3ibMjK95 M2oAniw+rpONMOXtmC28ZGpxlxValjmC =SPIc -----END PGP SIGNATURE----- ------------------------------------------------------------------------------ _______________________________________________ Prex-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/prex-devel
