QEMU

  1. Bug #1796520
  2. Comment #2

Comment 2 for bug 1796520

Revision history for this message
Peter Maydell (pmaydell) wrote :

I can reproduce this bug, but I'm not sure what QEMU is doing wrong. Looking at the "SH4 Software Manual", it definitely says that if the FPSCR.PR bit is 0 then the 'frchg' and 'fschg' instructions should both trap.

The 'frchg' that autogen is hitting is the one in glibc's "getcontext" implementation:
https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/sh/sh4/getcontext.S;hb=b6d2c4475d5abc05dd009575b90556bdd3c78ad0#l70

QEMU linux-user mode runs with FPSCR=0x000800000, which is "FPSCR.PR == 1", ie "double precision". This seems to match what the kernel has for its FPSCR_INIT value.

Are you in a position to test what the actual hardware/real Linux kernel using for its FPSCR value when running sh4 userspace binaries ?