Comment 0 for bug 1861605

In that commit the env->llval value is loaded as an unsigned value (instead of sign-extended as before and therefore the CMPXCHG in gen_st_cond() in translate.c fails.

I have committed a fix for this issue as https://github.com/CTSRD-CHERI/qemu/commit/a18d80c629989d002794f558968e1561edaf3dfd

An alternative solution would be to change the cmpxchg line to perform a non-sign-extended compare, i.e. replace
    tcg_gen_atomic_cmpxchg_tl(t0, addr, cpu_llval, val,
                              eva ? MIPS_HFLAG_UM : ctx->mem_idx, tcg_mo);
with
    tcg_gen_atomic_cmpxchg_tl(t0, addr, cpu_llval, val,
                              eva ? MIPS_HFLAG_UM : ctx->mem_idx, tcg_mo & ~MO_SIGN);

I cannot send this patch to the QEMU mailing list as I am not able to setup git-send-email.
Feel free to apply this commit or the alternative solution.