[Qemu-devel] [Bug 883136] Re: qemu on ARM hosts aborts on startup because makecontext() always fails

[Dr. David Alan Gilbert]

Attached is a 1st cut of a makecontext/setcontext/getcontext/swapcontext set 
for ARM - not ready to go into libc yet;
currently it builds standalone and links (and passes) with a test of mine.  
Next stop libc and a lot of cleanup.


** Changed in: qemu-linaro
     Assignee: (unassigned) => Dr. David Alan Gilbert (davidgil-uk)

** Attachment added: "Start of a set of context routines"
   
https://bugs.launchpad.net/qemu-linaro/+bug/883136/+attachment/2642884/+files/allcontext.S

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https://bugs.launchpad.net/bugs/883136

Title:
  qemu on ARM hosts aborts on startup because makecontext() always fails

Status in QEMU:
  New
Status in Linaro QEMU:
  New

Bug description:
  qemu has recently grown a coroutines implementation. There are two
  versions, one using the makecontext/setcontext/swapcontext functions
  from ucontext.h, and one falling back to implementing coroutines as
  separate glib threads. configure chooses the former if the platform
  has a makecontext().

  Unfortunately ARM eglibc provides a makecontext() which always fails
  ENOSYS, which means the configure check passes but when qemu starts it
  abort()s.

  The best fix for this is probably going to involve making the
  coroutine implementation runtime-selectable.

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