Gilles Chanteperdrix wrote: > Alexis Berlemont wrote: >> Hi, >> >> On Friday 17 October 2008 06:46, [EMAIL PROTECTED] wrote: >>> No comments or ideas? Providing this feature is essential for our CPCI >>> drivers. We have to port some Linux applications to Xenomai which use that >>> mmap stuff intensely. >>> >>> Thanks again! >>> >>> Thomas >>> >>>> -----Ursprüngliche Nachricht----- >>>> Von: [EMAIL PROTECTED] >>>> [mailto:[EMAIL PROTECTED] Im Auftrag von >>>> [EMAIL PROTECTED] >>>> Gesendet: Mittwoch, 8. Oktober 2008 11:49 >>>> An: [email protected] >>>> Betreff: [Xenomai-help] rtdm_iomap_to_user on PPC >>>> >>>> Hello, >>>> >>>> in the following thread I was asking for a solution to use >>>> rtdm_iomap_to_user() on PPC (MPC5200, Denx 2.4.25) >> >> In 2.4 kernel, rtdm_iomap_to_user() is based on the function >> remap_page_range >> (with vma->vm_flags |= VM_RESERVED). >> >> Once, I had to develop a classical Linux driver (for PPC) which provided >> mmap >> functionalites so as to let a user application mmap a buffer allocated >> thanks >> to __get_free_pages(). >> >> On a 2.6 kernel, I used remap_pfn_range() and it works great but on 2.4 >> kernel >> the function remap_page_range() did not work as I expected. I had a quick >> look on its implementation and I found that instead of mapping my buffer it >> mapped newly allocated zeroed pages (if my memories are correct). >> >> If I remember well, these pages were allocated in lazy mode. That could >> explain the freeze of your whole system: in case a RT application in primary >> mode tries to access the mmapped buffer. > > Well, normally, the fault should cause the RT application to switch to > secondary mode and be handled gracefully from there, unless there is a > bug hidden in Xenomai or I-pipe. Besides, RT applications usually use > "mlockall", so the kernel should make all the pages present and not rely > on further faults (at least, is it how it works on 2.6). >
powerpc may still trigger minor faults upon TLB misses though. That arch has a software-assisted MMU. -- Philippe. _______________________________________________ Xenomai-help mailing list [email protected] https://mail.gna.org/listinfo/xenomai-help
