Hi Ramana, On 27 June 2017 at 18:01, Ramana Radhakrishnan <ramana.radhakrish...@foss.arm.com> wrote: > On 27/06/17 02:20, Kugan Vivekanandarajah wrote: >> >> https://gcc.gnu.org/ml/gcc-patches/2016-03/msg00614.html added this >> workaround to get kernel building with when TARGET_FIX_ERR_A53_843419 >> is enabled. >> >> This was added to support building kernel loadable modules. In kernel, >> when CONFIG_ARM64_ERRATUM_843419 is selected, the relocation needed >> for ADRP/LDR (R_AARCH64_ADR_PREL_PG_HI21 and >> R_AARCH64_ADR_PREL_PG_HI21_NC are removed from the kernel to avoid >> loading objects with possibly offending sequence). Thus, it could only >> support pc relative literal loads. >> >> However, the following patch was posted to kernel to add >> -mpc-relative-literal-loads >> http://www.spinics.net/lists/arm-kernel/msg476149.html >> >> -mpc-relative-literal-loads is unconditionally added to the kernel >> build as can be seen from: >> https://github.com/torvalds/linux/blob/master/arch/arm64/Makefile >> >> Therefore this patch removes the hunk so that applications like >> SPECcpu2017's 521/621.wrf can be built (with LTO in this case) without >> -mno-pc-relative-literal-loads > > > Is that because your compiler has defaulted to -mpc-relative-literal-loads > because it has the workaround enabled by default ? I'm curious as to why > others haven't seen this issue. >
If TARGET_FIX_ERR_A53_843419 is selected, compiler defaults to -mpc-relative-literal-loads unless we explicitly specify -mno-pc-relative-literal-loads. Linaro toolchain is built with TARGET_FIX_ERR_A53_843419. This linking of TARGET_FIX_ERR_A53_843419 and -mpc-relative-literal-loads should now be relaxed since the kernel explicitly uses -mpc-relative-literal-loads. This 1MiB issue should be very rarely seen even before you fixed it. Thanks, Kugan > regards > Ramana
