From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [103.22.144.67]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id B1F5A1A0017 for ; Wed, 7 Oct 2015 10:14:20 +1100 (AEDT) Received: from na01-bn1-obe.outbound.protection.outlook.com (mail-bn1bn0107.outbound.protection.outlook.com [157.56.110.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id EC007140D93 for ; Wed, 7 Oct 2015 10:14:19 +1100 (AEDT) Message-ID: <1444171233.5336.310.camel@freescale.com> Subject: Re: [kexec-lite PATCH V2] trampoline: Reset primary cpu endian to big-endian From: Scott Wood To: CC: , Date: Tue, 6 Oct 2015 17:40:33 -0500 In-Reply-To: <559C9DC1.30201@au1.ibm.com> References: <1436326178-17021-1-git-send-email-sam.mj@au1.ibm.com> <1436326636.2658.68.camel@freescale.com> <559C9DC1.30201@au1.ibm.com> Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2015-07-08 at 13:49 +1000, Samuel Mendoza-Jonas wrote: > On 08/07/15 13:37, Scott Wood wrote: > > On Wed, 2015-07-08 at 13:29 +1000, Samuel Mendoza-Jonas wrote: > > > Older big-endian ppc64 kernels don't include the FIXUP_ENDIAN check, > > > meaning if we kexec from a little-endian kernel the target kernel will > > > fail to boot. > > > Returning to big-endian before we enter the target kernel ensures that > > > the target kernel can boot whether or not it includes FIXUP_ENDIAN. > > > > > > Signed-off-by: Samuel Mendoza-Jonas > > > --- > > > V2: As suggested by Anton take advantage of the rfid call and switch off > > > MSR_LE and branch to the target kernel in the same step. > > > > > > kexec_trampoline.S | 11 +++++++++-- > > > 1 file changed, 9 insertions(+), 2 deletions(-) > > > > > > diff --git a/kexec_trampoline.S b/kexec_trampoline.S > > > index a3eb314..3751112 100644 > > > --- a/kexec_trampoline.S > > > +++ b/kexec_trampoline.S > > > @@ -88,8 +88,15 @@ start: > > > > > > li r5,0 > > > > > > - mtctr r4 > > > - bctr > > > + mtsrr0 r4 > > > + > > > + mfmsr r5 > > > + clrrdi r5,r5,1 /* Clear MSR_LE */ > > > + mtsrr1 r5 > > > + > > > + li r5,0 > > > + > > > + rfid > > > > Is kexec-lite meant to be specific to book3s-64? The README just says "A > > simple kexec for flattened device tree platforms" and I see a > > __powerpc64__ > > ifdef in kexec_trampoline.S (but not in the above patch)... > > > > -Scott > > > > I believe that particular ifdef is to check if we're little-endian when > reading > the device tree, but that's still a good point - I'll check with Anton. It looks like this ended up going into main kexec, which means I get to find some way to distinguish book3s from book3e to avoid that rfid. Yay. -Scott