On Tue, Jan 26, 2016 at 2:42 PM, Christophe Lyon <christophe.l...@linaro.org> wrote: > Hi, > > This is a followup to PR63304. > > As discussed in bugzilla, this patch disables pcrelative_literal_loads > when -mfix-cortex-a53-843419 (or its default configure option) is > used. > > I copied the behavior of -mfix-cortex-a53-835769 (e.g. in > aarch64_can_inline_p), and I have tested by building the Linux kernel > using -mfix-cortex-a53-843419 and checked that > R_AARCH64_ADR_PREL_PG_HI21 relocations are not emitted anymore (under > CONFIG_ARM64_ERRATUM_843419). > > For reference, this is motivated by: > https://bugs.linaro.org/show_bug.cgi?id=1994
I think we need a bug report for this in the GCC bugzilla targeting GCC 6 and have a reference to that in addition to PR63304 as this is broken behaviour in gcc trunk with respect to the erratum fixup. There are 2 solutions to this - one is to put out address constants in the large memory model with the mov / movk instruction sequences but then that wouldn't work with older released kernels and require changes to the kernel loader and the other being this where we turn on PC relative literal loads for the erratum fixup. I personally think that this solution is probably sensible during stage4 but I cannot approve changes to the AArch64 backend. The only question I have about this implementation in the sources based on a cursory look at the patch is whether this ends up working reliably with LTO ? regards Ramana > and further details on Launchpad: > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1533009 > > OK for trunk? > > Thanks, > > Christophe.
