From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 17036C3F68F for ; Fri, 31 Jan 2020 09:07:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EA52B20CC7 for ; Fri, 31 Jan 2020 09:07:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728254AbgAaJHA (ORCPT ); Fri, 31 Jan 2020 04:07:00 -0500 Received: from mail-ot1-f66.google.com ([209.85.210.66]:40908 "EHLO mail-ot1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728181AbgAaJG7 (ORCPT ); Fri, 31 Jan 2020 04:06:59 -0500 Received: by mail-ot1-f66.google.com with SMTP id i6so5906075otr.7 for ; Fri, 31 Jan 2020 01:06:59 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=FD1m1C7Z6owu7pJKCcZNi0kfjnO20uBFbl49wSgK5Lg=; b=hle8MrtlObbp8du0+KnsTcFFRKRJGmAa/SeuW6xqbXWTh6BX+cc9XkiWMy6K0324Oh Y4j15FnY57MLGdpt93p3OheNy7jmhyzS9XEC04vFiyE9hIYV3oJkxOBdwwJ+w59erd+I M/PFHx5c4tA1KJlBG7jro/bnZQKPa/YbpjftnLWcQD0xwTEpZ19RtvAAxkZCpduRLAmZ bhz07Xa6a/bPDBp0Fp2/Mhq13Lcpaql9dLmgGJkz39Bp5qIDISCbTuCUKuXBszzwUKP7 o5gqqB63cCWsq7PEuc5/BNREGie/NZvxRj7QTemHY4lRi7QPnCwXtXKvz5aQgHK26IsL p+jQ== X-Gm-Message-State: APjAAAUAidzduP409qFszsqJ3XQ7yJAlvvkXS0deKpkT8F6/pkB4yvCp ZxcuU3uQT7d/mJVAqWVopzB1m0Fa0zlj+abFxAuUtA== X-Google-Smtp-Source: APXvYqxXnQrTWkpOmfZ4c1F1M3YsJErcFXJpAlowXPQwo2N4eVzTPJn2pP+D0bi+mHOGRWxfvp5vAPdvsTIebEfZIQg= X-Received: by 2002:a05:6830:1d55:: with SMTP id p21mr6833651oth.145.1580461618754; Fri, 31 Jan 2020 01:06:58 -0800 (PST) MIME-Version: 1.0 References: <20200130191049.190569-1-edumazet@google.com> In-Reply-To: From: Geert Uytterhoeven Date: Fri, 31 Jan 2020 10:06:47 +0100 Message-ID: Subject: Re: [PATCH] dma-debug: dynamic allocation of hash table To: Robin Murphy Cc: Eric Dumazet , Christoph Hellwig , Joerg Roedel , Linux IOMMU , Eric Dumazet , linux-kernel Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Robin, On Fri, Jan 31, 2020 at 12:46 AM Robin Murphy wrote: > On 2020-01-30 7:10 pm, Eric Dumazet via iommu wrote: > > Increasing the size of dma_entry_hash size by 327680 bytes > > has reached some bootloaders limitations. > > [ That might warrant some further explanation - I don't quite follow how > this would relate to a bootloader specifically :/ ] Increasing the size of a static array increases kernel size. Some (all? ;-) bootloaders have limitations on the maximum size of a kernel image they can boot (usually something critical gets overwritten when handling a too large image). While boot loaders can be fixed and upgraded, this is usually much more cumbersome than updating the kernel. Besides, a static array always consumes valuable unswapable memory, even when the feature would not be used (e.g. disabled by a command line option). Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds