Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030400AbdLSNFO (ORCPT ); Tue, 19 Dec 2017 08:05:14 -0500 Received: from ozlabs.org ([103.22.144.67]:45033 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936344AbdLSNFG (ORCPT ); Tue, 19 Dec 2017 08:05:06 -0500 From: Michael Ellerman To: Rob Landley , Kernel Mailing List , linuxppc-dev@lists.ozlabs.org, Benjamin Herrenschmidt , Paul Mackerras Subject: Re: powerpc64 kernel panic if you disable CONFIG_PPC_TRANSACTIONAL_MEM? In-Reply-To: References: Date: Wed, 20 Dec 2017 00:05:00 +1100 Message-ID: <87shc698cj.fsf@concordia.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1675 Lines: 43 Rob Landley writes: > I just added a ppc64 target to https://github.com/landley/mkroot which > means I built 4.14 with the attached miniconfig and ran it with the > attached qemu command line, and it works fine as is but if you remove > the transactional mem line from the config the kernel panics instead > of launching a shell prompt: > > init[1]: unhandled signal 4 at 0000000010001a04 nip 0000000010001a04 > lr 000000001002ebe8 code 1 > Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004 > > CPU: 0 PID: 1 Comm: init Not tainted 4.14.0 #1 > Call Trace: > [c00000000e02fa40] [c0000000004ba730] dump_stack+0xb0/0xf0 (unreliable) > [c00000000e02fa80] [c0000000000602a0] panic+0x138/0x2f8 > [c00000000e02fb20] [c00000000006541c] do_exit+0xa9c/0xaa0 > [c00000000e02fbe0] [c0000000000654d8] do_group_exit+0x58/0xf0 > [c00000000e02fc20] [c000000000073274] get_signal+0x1c4/0x6b0 > [c00000000e02fd10] [c0000000000142a0] do_signal+0x60/0x290 > [c00000000e02fe00] [c00000000001461c] do_notify_resume+0x8c/0xd0 > [c00000000e02fe30] [c00000000000b630] ret_from_except_lite+0x5c/0x60 > Rebooting in 1 seconds.. I built it here and got: init[1]: unhandled signal 4 at 00000000100f3eb4 nip 00000000100f3eb4 lr 00000000100d1e38 code 1 Which looking at objdump is: 00000000100f3eb0 <_savevr_30>: 100f3eb0: e0 ff 80 39 li r12,-32 100f3eb4: ce 01 cc 7f stvx v30,r12,r0 stvx is an ALTIVEC (vmx) instruction, so you need a kernel built with CONFIG_ALTIVEC. When you turn on TRANSACTIONAL_MEM it selects ALTIVEC, so that's why enabling that "fixes" it for you. If you just add CONFIG_ALTIVEC=y it should work. cheers