Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752499AbbBQRHz (ORCPT ); Tue, 17 Feb 2015 12:07:55 -0500 Received: from mail-ob0-f176.google.com ([209.85.214.176]:34394 "EHLO mail-ob0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752248AbbBQRHw (ORCPT ); Tue, 17 Feb 2015 12:07:52 -0500 Message-ID: <54E37569.80508@landley.net> Date: Tue, 17 Feb 2015 11:07:53 -0600 From: Rob Landley User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-Version: 1.0 To: Pavel Machek , Jason Gunthorpe CC: Pantelis Antoniou , One Thousand Gnomes , atull , Greg Kroah-Hartman , hpa@zytor.com, Michal Simek , Michal Simek , Randy Dunlap , Linux Kernel Mailing List , devicetree@vger.kernel.org, robh+dt@kernel.org, Grant Likely , iws@ovro.caltech.edu, linux-doc@vger.kernel.org, Mark Brown , philip@balister.org, rubini@gnudd.com, Steffen Trumtrar , jason@lakedaemon.net, kyle.teske@ni.com, nico@linaro.org, Felipe Balbi , m.chehab@samsung.com, davidb@codeaurora.org, davem@davemloft.net, cesarb@cesarb.net, sameo@linux.intel.com, Andrew Morton , Linus Walleij , pawel.moll@arm.com, mark.rutland@arm.com, ijc+devicetree@hellion.org.uk, galak@codeaurora.org, devel@driverdev.osuosl.org, Alan Tull , dinguyen@opensource.altera.com, yvanderv@opensource.altera.com Subject: Re: [PATCH v8 2/4] fpga manager: add sysfs interface document References: <20150113200032.GA16205@obsidianresearch.com> <20150113222450.GA17475@obsidianresearch.com> <20150115184726.GA23247@obsidianresearch.com> <20150115204502.591bca1d@lxorguk.ukuu.org.uk> <20150121160151.453ba403@lxorguk.ukuu.org.uk> <20150121202700.GB4942@obsidianresearch.com> <20150215224006.GA5626@amd> In-Reply-To: <20150215224006.GA5626@amd> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2020 Lines: 46 On 02/15/2015 04:40 PM, Pavel Machek wrote: > On Wed 2015-01-21 13:27:00, Jason Gunthorpe wrote: >> On Wed, Jan 21, 2015 at 06:33:12PM +0200, Pantelis Antoniou wrote: >> My point is that the current firmware layer is overly cautious and >> FPGAs are very big. My current project on small Xilinx device has a >> 10MB programming file. The biggest Xilinx device today has a max >> bitfile size around 122MB. >> >> So keeping that much memory pinned in the kernel when I can prove it >> is uncessary for my system (either because there is no suspend/resume >> possibility, or because I know the CPU can always access the >> filesytem) is very undesirable. > > Well, your current device aalso has 1GB RAM, no? Unnecessarily pinning 10% of your ram is a good solution? > I'd say the general case is "store bitstream in RAM" we can add > optimalizations later. We _have_ a firmware loading layer that doesn't store other kinds of firmware in pinned kernel memory. I guess that was retroactively a bad idea. As was the "freeing kernel memory" part at the end of boot. There honestly are small embedded devices. Still. When you have your DRAM on the SOC instead of as an external chip, a gigabyte is not in the cards. If you're saying "Linux should not care about this niche, let's open ourselves to a new disruptive technology attack with that as its initial protected base, because the average kernel developer age is about 44 now and we're not really recruiting anybody younger than that, so we'll all be dead before we have to care about being replaced"... Rob (At $DAYJOB we're building a chip that runs off of induction current to retrofit monitoring sensors onto things. It currently has 64 megs of ram but they're trying to trim that _down_ to free up chip space.) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/