From mboxrd@z Thu Jan 1 00:00:00 1970 From: steve.mcintyre@linaro.org (Steve McIntyre) Date: Wed, 10 Apr 2013 19:24:15 +0100 Subject: Removal of NWFPE in its entirety, and VFP emulation code In-Reply-To: References: <20130410104002.GF14496@n2100.arm.linux.org.uk> Message-ID: <20130410182415.GD19224@einval.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Apr 10, 2013 at 01:30:35PM -0400, Nicolas Pitre wrote: >On Wed, 10 Apr 2013, Russell King - ARM Linux wrote: > >> I have just committed a patch to remove the arch/arm/nwfpe code from >> the kernel, and the VFP code emulating the FP operations. >> >> This I have done after it has been brought to my attention by the OSADL's >> GPL-violations project that the license for the softfloat library is >> incompatible with GPLv2. This is because the FSF have ruled that >> indemnification clauses consitute an "additional restriction" which is >> incompatible with the GPLv2 section 6. NWFPE contains the softfloat >> library, and VFP's emulation code is a derivative of softfloat. >> >> This will be very disruptive for ARMv4 and ARMv5 CPUs, which will no >> longer be able to run userspace with NWFPE support removed. A possible >> solution there is to resurrect FASTFPE support and merge that into >> mainline in place of NWFPE. FASTFPE's hooks are all present in the >> kernel, and it should just be a case of adding the FASTFPE code. >> However, FASTFPE is probably lacking GDB and signal stack support. >> (FastFPE's per-thread workspace is different from NWFPE.) > >A point worth mentioning is the EABI availability since 2006 which moved >away from FPA completely. A soft-float library in user space is used in >that case. Major ARM binary producers including all ARM distros moved >to EABI with user space soft-float since then as it is order of >magnitude faster than FPA emulation. So 99.99% of ARMv4 and ARMv5 users >are unlikely to be affected. > >So another option here might imply deprecating OABI support entirely, >given that it is useless without FPA and people keeping current with the >latest kernel are very likely to already use EABI user space. Plus, OABI is just about dead in major places like glibc too. Cheers, -- Steve McIntyre steve.mcintyre at linaro.org Linaro.org | Open source software for ARM SoCs