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From:   Michael Ellerman <mpe@ellerman.id.au>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de>
Cc:     linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        Guenter Roeck <linux@roeck-us.net>,
        Breno Leitao <leitao@debian.org>,
        Michal =?utf-8?Q?Such=C3=A1nek?= <msuchanek@suse.de>
Subject: Re: [PATCH 4.20 41/65] Revert "powerpc/tm: Unset MSR[TS] if not recheckpointing"
In-Reply-To: <20190113071140.GD5540@kroah.com>
References: <20190111131055.331350141@linuxfoundation.org> <20190111131102.136630542@linuxfoundation.org> <1547328527@msgid.manchmal.in-ulm.de> <20190113071140.GD5540@kroah.com>
Date:   Mon, 14 Jan 2019 11:00:25 +1100
Message-ID: <87pnt0ds6e.fsf@concordia.ellerman.id.au>
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Greg Kroah-Hartman <gregkh@linuxfoundation.org> writes:
> On Sat, Jan 12, 2019 at 10:35:59PM +0100, Christoph Biedl wrote:
>> Greg Kroah-Hartman wrote...
>> 
>> > 4.20-stable review patch.  If anyone has any objections, please let me know.
>> >
>> > ------------------
>> >
>> > From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
>> >
>> > This reverts commit d412deb85a4aada382352a8202beb7af8921cd53 which is
>> > commit 6f5b9f018f4c7686fd944d920209d1382d320e4e upstream.
>> >
>> > It breaks the powerpc build, so drop it from the tree until a fix goes
>> > upstream.
>> 
>> Is this necessary on 4.20? The build failures I reported were on 4.19
>> only. The 4.20.2-rc1 kernel for my Powermac G5 builds with and without
>> that patch, both boot fine, no visible differences. Again however, Breno
>> is authoritative here.
>
> If there's no difference on 4.20, then maybe it's not needed there?  :)
>
> And yes, I would like confirmation from Breno as well.

You shouldn't need the revert on 4.20.

In 4.20 we changed how MSR_TM_ACTIVE() is defined, which means commit
6f5b9f018f4c ("powerpc/tm: Unset MSR[TS] if not recheckpointing") should
build fine on 4.20.

For 4.19 and earlier MSR_TM_ACTIVE() is different and that's what's
causing the build error.

I have a fix queued in my fixes tree and will push it to Linus in the
next few days.

cheers