3 ms·

Meanwhile I have seen nothing from QNX or Integrity...

jacquesm 9y ago
I wonder to what extent QNX would be affected. It all depends on whether or not they map their micro kernel into the same address space as the application, for a micro kernel there is absolutely no reason to do that, the only things you might want to re-map are the message buffers and that can be done with some page table trickery.
- dfox 9y ago
  QNX does map it's kernel onto high end of user VM space. Due to how i386 TLB works (ie. no ASID) doing that is essentially required to get reasonable performance, micro kernel or not.
  - cesarb 9y ago
    If the kernel has no sensitive state (believable for a microkernel), what matters is whether it maps the physical memory in its kernel space.
    - dfox 9y ago
      QNX 6.5 apparently maps first 256MB of physical memory into kernel space at fixed location. Also I believe that QNX's kernel memory contains region that maps to pages of user space memory of other processes (as part of the message passing mechanism, but I'm not exactly sure that I understand correctly how it actually works).
  - jschwartzi 9y ago
    What about on ARM?
    - jacquesm 9y ago
      Has QNX been ported to ARM? Interesting! edit: apparently it has been: http://www.qnx.com/developers/docs/6.5.0/index.jsp?topic=%2Fcom.qnx.doc.neutrino_technotes%2FQNX_for_ARMv7_Cortex_Processors.html http://www.qnx.com/developers/docs/6.5.0/index.jsp?topic=%2F...
      - jschwartzi 9y ago
        I'm using 6.5.0 SP1 in an ARM-based project. The documentation on their Screen graphics stack leaves something to be desired but otherwise it's a reasonably competent system.
      - dfox 9y ago
        I would assume that majority of QNX deployments are on ARM these days and also ARM is the only platform supported by complete QNX "ecosystem" as some parts are not available for x86 (which is the only other currently supported platform). Wikipedia states that supported platforms historically were i386, PowerPC, MIPS, SuperH and ARM. And I would not be too surprised if there was support for Altera Nios-II with MMU in the times when QNX was owned by Harman (As at least the touch screen part of some versions of Harman made Audi MMI is based on NiosII).
JdeBP 9y ago
If you are looking for something from the microkenel world, there is a statement dealing with Genode OS. * https://news.ycombinator.com/item?id=16084617 https://news.ycombinator.com/item?id=16084617

I wonder to what extent QNX would be affected. It all depends on whether or not they map their micro kernel into the same address space as the application, for a micro kernel there is absolutely no reason to do that, the only things you might want to re-map are the message buffers and that can be done with some page table trickery.

dfox 9y ago
QNX does map it's kernel onto high end of user VM space. Due to how i386 TLB works (ie. no ASID) doing that is essentially required to get reasonable performance, micro kernel or not.
- cesarb 9y ago
  If the kernel has no sensitive state (believable for a microkernel), what matters is whether it maps the physical memory in its kernel space.
  - dfox 9y ago
    QNX 6.5 apparently maps first 256MB of physical memory into kernel space at fixed location. Also I believe that QNX's kernel memory contains region that maps to pages of user space memory of other processes (as part of the message passing mechanism, but I'm not exactly sure that I understand correctly how it actually works).
- jschwartzi 9y ago
  What about on ARM?
  - jacquesm 9y ago
    Has QNX been ported to ARM? Interesting! edit: apparently it has been: http://www.qnx.com/developers/docs/6.5.0/index.jsp?topic=%2Fcom.qnx.doc.neutrino_technotes%2FQNX_for_ARMv7_Cortex_Processors.html http://www.qnx.com/developers/docs/6.5.0/index.jsp?topic=%2F...
    - jschwartzi 9y ago
      I'm using 6.5.0 SP1 in an ARM-based project. The documentation on their Screen graphics stack leaves something to be desired but otherwise it's a reasonably competent system.
    - dfox 9y ago
      I would assume that majority of QNX deployments are on ARM these days and also ARM is the only platform supported by complete QNX "ecosystem" as some parts are not available for x86 (which is the only other currently supported platform). Wikipedia states that supported platforms historically were i386, PowerPC, MIPS, SuperH and ARM. And I would not be too surprised if there was support for Altera Nios-II with MMU in the times when QNX was owned by Harman (As at least the touch screen part of some versions of Harman made Audi MMI is based on NiosII).

JdeBP 9y ago

If you are looking for something from the microkenel world, there is a statement dealing with Genode OS. * https://news.ycombinator.com/item?id=16084617 https://news.ycombinator.com/item?id=16084617