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[122.58.176.92]) by smtp.gmail.com with ESMTPSA id q187sm6087950pfq.128.2018.11.16.19.00.41 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 16 Nov 2018 19:00:47 -0800 (PST) Subject: Re: [RFC PATCH 01/13] arm: Fix mutual exclusion in arch_gettimeoffset To: Finn Thain , Russell King - ARM Linux References: <20181112083422.GA19695@infradead.org> <20181113092012.GI30658@n2100.armlinux.org.uk> <20181113234336.GP30658@n2100.armlinux.org.uk> <20181114141632.GT30658@n2100.armlinux.org.uk> <20181116174705.GY30658@n2100.armlinux.org.uk> Cc: Christoph Hellwig , Geert Uytterhoeven , Arnd Bergmann , Stephen N Chivers , Thomas Gleixner , Daniel Lezcano , John Stultz , linux-m68k@lists.linux-m68k.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org From: Michael Schmitz Message-ID: Date: Sat, 17 Nov 2018 16:00:39 +1300 User-Agent: Mozilla/5.0 (X11; Linux ppc; rv:45.0) Gecko/20100101 Icedove/45.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Finn, Am 17.11.2018 um 11:49 schrieb Finn Thain: > On Fri, 16 Nov 2018, Russell King - ARM Linux wrote: > >> >> The EBSA110 is probably in a similar boat - I don't remember whether it >> had 16MB or 32MB as the maximal amount of memory, but memory was getting >> tight with some kernels even running a minimalist userspace. >> >> So, it's probably time to say goodbyte to the kernel support for these >> platforms. >> > > Your call. > > Note that removing code from mainline won't help users obtain older, > smaller, -stable kernel releases, free from the bug we were discussing. > (The bug appeared in Linux v2.6.32.) > > BTW, if you did want to boot Linux on a 16 MB system, you do have some > options. > > https://lwn.net/Articles/741494/ > https://lwn.net/Articles/608945/ > https://tiny.wiki.kernel.org/ > > Contributing to this kind of effort probably has value for IoT > deployments. I suspect it also cuts a small amount of bloat from a large > number of other Linux systems. I boot 4.19 on a system with 14 MB RAM - 10 MB remain for user space once the kernel loads. After remote login, 4 MB of that remain free for buffers or user code (1.5 MB swapped). That's with sysvinit - Christian tried to boot a systemd userland on his Falcon once, and ran out of memory before swap could be activated. I shouldn't say 16 or 32 MB are hopeless. And the 2.6 kernels were a lot more sluggish to my recollection. Cheers, Michael