On Sun, Oct 19, 2014 at 7:48 AM, Pavel Pisa <p...@control.felk.cvut.cz> wrote: > Hello Gedare and Joel, > > On Friday 17 of October 2014 10:17:24 Jan Dolezal wrote: >> prevents possible mkdir and cd error when parents of build >> directory are missing >> --- >> do_it | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/do_it b/do_it > > please push Jan Dolezals's patch to > > http://git.rtems.org/rtems-graphics-toolkit/ > > it corrects Nano-X build. > Thanks Pavel. I didn't see it among the warning patches.
> Then there is quite large amount of patches for RTEM which > Jan Dolezal works on to provide PC VESA BIOS Extension support > for RTEMS. Mode selection is planned only during RTEMS startup > before interrupts are enabled for now. > > Runtime VESA BIOS calls are extremely problematic. > > - there is defined protected VBE 3.0 entry point, but it is not present > in QEMU VESA BIOS and on the most of the tested cards. Even if present > on some cards, it seems to be broken according to our attempts to use it. > This solution was my initial idea, but proved to be unusable > and cost enormous time. > - switching to real mode is no option after startup for RTOS - to work > at least potentially reliably requires to block all interrupts > on PIC/APIC/LAPIC level > - VM86 mode would be doable but requires significant additional > complexity and overhead for task switch or use separate TSS > nonsense for each task > - the last analyzed interresting solution is to include x86 instruction > set interpreter in RTEMS which would allow to run BIOS x86 > real code sandboxed and with additional memory ranges protection > and with minimal impact on other RT code running in parallel. > This would be nice to do, allows to use x86 PCI VESA BIOS cards > on other PCI enabled architectures but it is above our current > capabilities and time constraints. On the other hand we can provide > example from NOVA microkernel which achieved and uses this goal. > This last option seems quite interesting. Can you link to the example or any doc on how it is done? > So the current goal is mode setup during RTEMS startup but real mode > functions calls done from protected C code to achieve readability > and flexibility. This is approach which Grub and many other systems > and loaders uses so it should be most reliable and tested on real > hardware. > > I am bringing actual Jan Dolezal's work to your attention now > to do get some initial suggestions, then I expect that patches > would be be send for review to RTEMS mailinglist. > Probably during this month. > Great. > The complete work > > https://github.com/dolezaljan/rtems/commits/master > > The key changes for discussion and possible correction > of work direction > > - added header for VESA BIOS Extension > prepared from scratch to ensure clean license for RTEMS > > - GDT entries manipulation functions + > GDT entries information getting functions + ... > GDT extension to more entries and changes in RTEMS > global GDT manipulation functions to allow setup > entries required for switching to real mode > These changes are in RTEMS x86 critical shared > code, so review by more people is needed > Joel is primary x86 maintainer around here. He should comment when they come through. > - actual VESA BIOS calls and mode witching > this is not so critical, because it is optional > and does not influence code which does not use > new graphics features > > I would be happy if you help with review process. > Do you want to have patch series on GitHub first > or should be patches sent to RTEMS devel directly? > They probably won't get looked at on GitHub unless you ask someone directly to have a look and provide the exact link. -Gedare > Best wishes, > > Pavel _______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
