On Thu, Dec 03, 2009 at 05:09:38PM +0000, Thomas Klein wrote: > This might be the initial plan. > But is this true?
It is true because a typical implementation of this function has no need to clobber registers. For instance, glibc's calls a kernel helper this way: 0x00015810 <__aeabi_read_tp+0>: mvn r0, #61440 ; 0xf000 0x00015814 <__aeabi_read_tp+4>: sub pc, r0, #31 The kernel helper reads from a fixed location or a hardware register, both of which are a single instruction. No temporary registers are required. > A "bl __aeabi_read_tp" call does not exchanging the mode. > So the program simply crashes. The linker is responsibe for converting bl to blx, or for inserting mode changing stubs. It is also responsible for long calls. Unless you're using a really old linker, I can't see why you would have any problems. Do you have a concrete problem? > Is the implementation still incomplete? No. It's been finished for two years or more. -- Daniel Jacobowitz CodeSourcery
