Re: port-powerpc/51366 kernel for powerpc/ibm4xx miscompiled by gcc >= 4.8.5

[Rin Okuyama <rokuyama%rk.phys.keio.ac.jp@localhost>]

The following reply was made to PR port-powerpc/51366; it has been noted by GNATS.

From: Rin Okuyama <rokuyama%rk.phys.keio.ac.jp@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: port-powerpc/51366 kernel for powerpc/ibm4xx miscompiled by gcc
 >= 4.8.5
Date: Sun, 11 Dec 2016 02:09:50 +0900

 I've found the cause of this failure. The index of sprg for pid is
 different between generic ppc and IBM 405; 48 and 945, respectively.
 Therefore, for example, "mfpid N" is assembled into "mfspr rN, 48"
 for generic ppc, but it should be "mfspr rN, 945" for IBM 405.
 
 Since GCC >= 4.8.5 passes ".machine ppc" pseudo-op to assembler,
 "m[ft]pid" instructions in inline assembler codes are misassembled
 for IBM 405, even if -mcpu=405 or -Wa,-m405 options are specified.