On Tue, Oct 26, 2010 at 2:38 AM, Chris Tyler chris@tylers.info wrote:
On Mon, 2010-10-25 at 21:27 -0400, Adam Goode wrote:
On 10/25/2010 07:31 PM, Dennis Gilmore wrote:
Id like to have00079ca0-0130hat we need to do to support both software floating point and hardware floating point support. I had been under the impression that all we would need to do is to build glibc with hardfp support. however that may not be the case. and we may need to build everything with hardfp support.
this is just to get discussion rolling
See this thread for a little context: http://cygwin.com/ml/libc-ports/2009-04/msg00020.html
Basically, soft floating point on ARM is done with helper functions. By default, these are statically linked in, but they do not need to be. If you dynamically link in the aeabi floating point helper code (basically libgcc) and have a multilib glibc, then there is the ability to have softfp binaries that can take advantage of hardfp when available. These binaries will be slower than real hardfp binaries though. And it is not clear that multilib alone is sufficient, it may be that the new IFUNC stuff is really needed for good performance across different VFP variants.
Adam
Of the devices I've seen so far, the armv5 devices have all been softfp, and the armv7 devices have been hardfp. Are there any widely-used exceptions to this pattern?
There's discussions on the MeeGo dev list at the moment about moving to it for all supported platforms at the moment.
Peter