On Mon, Mar 29, 2021 at 01:09:18PM +0800, YunQiang Su wrote:
YunQiang Su yunqiang.su@cipunited.com 于2021年3月22日周一 上午10:00写道：
The MIPS FPU may have 3 mode: FR=0: MIPS I style, all of the FPR are single. FR=1: all 32 FPR can be double. FRE: redirecting the rw of odd-FPR to the upper 32bit of even-double FPR.
The binary may have 3 mode: FP32: can only work with FR=0 and FRE mode FPXX: can work with all of FR=0/FR=1/FRE mode. FP64: can only work with FR=1 mode
Some binary, for example the output of golang, may be mark as FPXX, while in fact they are FP32. It is caused by the bug of design and linker: Object produced by pure Go has no FP annotation while in fact they are FP32; if we link them with the C module which marked as FPXX, the result will be marked as FPXX. If these fake-FPXX binaries is executed in FR=1 mode, some problem will happen.
In Golang, now we add the FP32 annotation, so the future golang programs won't have this problem. While for the existing binaries, we need a kernel workaround.
We meet a new problem in Debian: with the O32_FP64 enabled kernel, mips64el may also be affected. https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=983583
hmm, raising this issue in this context before knowing more details, feels very trigger happy to me and this doesn't help accepting anything, jfyi...
Could you please provide a link for downloading a golang binary, which would need this patch to run ?
Thomas.