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From:   Florian Weimer <fweimer@redhat.com>
To:     "Theodore Ts'o" <tytso@mit.edu>
Cc:     Russell King - ARM Linux admin <linux@armlinux.org.uk>,
        Arnd Bergmann <arnd@kernel.org>, Will Deacon <will@kernel.org>,
        linux-toolchains@vger.kernel.org,
        Mark Rutland <mark.rutland@arm.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        Ext4 Developers List <linux-ext4@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: Aarch64 EXT4FS inode checksum failures - seems to be weak
 memory ordering issues
References: <20210105154726.GD1551@shell.armlinux.org.uk>
        <20210106115359.GB26994@C02TD0UTHF1T.local>
        <20210106135253.GJ1551@shell.armlinux.org.uk>
        <20210106172033.GA2165@willie-the-truck>
        <20210106223223.GM1551@shell.armlinux.org.uk>
        <20210107111841.GN1551@shell.armlinux.org.uk>
        <20210107124506.GO1551@shell.armlinux.org.uk>
        <CAK8P3a2TXPfFpgy+XjpDzOqt1qpDxufwiD-BLNbn4W_jpGp98g@mail.gmail.com>
        <20210107133747.GP1551@shell.armlinux.org.uk>
        <X/c2aqSvYCaB9sR6@mit.edu>
Date:   Thu, 07 Jan 2021 18:00:21 +0100
In-Reply-To: <X/c2aqSvYCaB9sR6@mit.edu> (Theodore Ts'o's message of "Thu, 7
        Jan 2021 11:27:22 -0500")
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* Theodore Ts'o:

> On Thu, Jan 07, 2021 at 01:37:47PM +0000, Russell King - ARM Linux admin wrote:
>> > The gcc bugzilla mentions backports into gcc-linaro, but I do not see
>> > them in my git history.
>> 
>> So, do we raise the minimum gcc version for the kernel as a whole to 5.1
>> or just for aarch64?
>
> Russell, Arnd, thanks so much for tracking down the root cause of the
> bug!
>
> I will note that RHEL 7 uses gcc 4.8.  I personally don't have an
> objections to requiring developers using RHEL 7 to have to install a
> more modern gcc (since I use Debian Testing and gcc 10.2.1, myself,
> and gcc 5.1 is so five years ago :-), but I could imagine that being
> considered inconvenient for some.

Actually, RHEL 7 should have the fix (internal bug #1362635, curiously
we encountered it in the *XFS* CRC calculation code back then).

My understanding is that RHEL 7 aarch64 support ceased completely about
a month ago, so that shouldn't be an argument against bumping the
minimum version requirement to 5.1.

Thanks,
Florian
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