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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 718F1C54EBD for ; Thu, 12 Jan 2023 07:01:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235845AbjALHBg (ORCPT ); Thu, 12 Jan 2023 02:01:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43880 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235142AbjALHBe (ORCPT ); Thu, 12 Jan 2023 02:01:34 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9A13A4BD74; Wed, 11 Jan 2023 23:01:33 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id E868261F1B; Thu, 12 Jan 2023 07:01:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D35FDC433D2; Thu, 12 Jan 2023 07:01:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1673506892; bh=JxyJhWfXS57T6gcOSacg+7qJX6CHLfeccMEKVqrqynw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=RYqh+ZGyHRfcu59btf13SDBY9/gzz+74U/rRjnP0IhvdOu0teBqMkqMmxJX6kAGNZ GyL8W5jD0bcdEKqPtXjJ6SPphA8QDotJ855sAmbbE8ugQFCul1oS8nrkhpw3W7z/eP Bi1PIg68WLqzUZTTX9yMo7mxXyhJzhpc/dVOoF/RUamW04uvFfoyy9f7OdS0OvRfLA Vg8nvLXKcq0ZIYJB7QgyXpp/o8x18dXHVFh7FCZouQw5VaQOvP7h6yzRmjoEzGgb+k ZFF4zS5+Rj+gBeT55m8OuXQ3jRTcCX0C7qU1gwM1RrL4d/9l34lDqVVmxBgsoHSsDl RTZkqO7gWuV8Q== Date: Thu, 12 Jan 2023 16:01:28 +0900 From: Masami Hiramatsu (Google) To: Souradeep Chowdhury Cc: , Bjorn Andersson , , , "Sai Prakash Ranjan" , Sibi Sankar , Rajendra Nayak Subject: Re: [PATCH V0 1/1] bootconfig: Increase max size of bootconfig from 32 KB to 256 KB for DCC support Message-Id: <20230112160128.600f9e7257d67aa63a5fbcb9@kernel.org> In-Reply-To: <9545ca51-ccda-64f0-bdd4-3b53e06785ad@quicinc.com> References: <654357bcbfd3974072a558c494a51edafaa73e1a.1673261071.git.quic_schowdhu@quicinc.com> <20230110001820.5ca81344286f614ed4ccec77@kernel.org> <20230110234643.7bbd340ece99c28f25fe7ad7@kernel.org> <9545ca51-ccda-64f0-bdd4-3b53e06785ad@quicinc.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Tue, 10 Jan 2023 20:38:54 +0530 Souradeep Chowdhury wrote: > > > On 1/10/2023 8:16 PM, Masami Hiramatsu (Google) wrote: > > On Tue, 10 Jan 2023 17:26:07 +0530 > > Souradeep Chowdhury wrote: > > > >> > >> > >> On 1/9/2023 8:48 PM, Masami Hiramatsu (Google) wrote: > >>> On Mon, 9 Jan 2023 20:01:05 +0530 > >>> Souradeep Chowdhury wrote: > >>> > >>>> Increasing the memory size of bootconfig to be able to handle a max number of > >>>> 8192 nodes to be fitted in memory size of 256KB. > >>> > >>> Sorry, but you missed the 'xbc_node::data' stores the index of the data and > >>> that is uint16_t. So the XBC_DATA_MAX is fixed limitation. > >>> > >>> The number of nodes (XBC_NODE_MAX) can be expanded because I just decided it > >>> to keep the pre-compiled array size ~8KB. Maybe expanding it to 64KB just > >>> increase the size of kernel on init memory (and freed after boot). > >>> > >>> Could you tell me why you need such a big data for your DCC? > >>> > >>> Thank you, > >> > >> DCC is a debugging tool used in qcom which is needed to debug crashes > >> that can happen at boot-time. For debugging purposes a large number of > >> registers need to be configured in DCC driver which is to be fed via the > >> bootconfig file. For that we need to expand the nodes as well as memory > >> for using bootconfig. > > > > Hmm, how many registers does DCC usually use? And how big the bootconfig > > file is usually? I have no idea about that. > > So a typical bootconfig file for consumption of DCC looks like as follows > > dcc_config { > link_list_0 { > qcom-curr-link-list = 6 > qcom-link-list = R_0x1781005c_1_apb, > R_0x1782005c_1_apb > } > link_list_1 { > qcom-curr-link-list = 5 > qcom-link-list = R_0x1784005c_1_apb > } > } > > The "qcom-link-list" field can have 1000s of register , based on that > max nodes is increased to 8192. OK, then the number of fields can be larger than 1000. I got it. > > > > >> Can you let us know the changes that you suggest for doing the same? Is > >> it fine to just increase the XBC_NODE_MAX, do we also need to > >> change the uint16_t to u32 for proper storing of index values? > > > > Expanding the number of max nodes is easy, just increase the XBC_NODE_MAX > > (must be less than 64k). That will also increase the memory consumption > > during the boot time even if the bootconfig is small. Anyway, it will be > > freed after boot, so it maybe OK. > > So since the limit is 64K, 8192 is a valid value for max nodes. Yes. Expanding the number of node is OK to me. > > > > > But expanding the size of max bootconfig needs to change the type of > > the 'data' field to uint32_t (since that will be used for building > > bootconfig tool) and you also must confirm that `tools/bootconfig/bootconfig` > > can be built and pass the test-bootconfig.sh. > > Hmm, comparing with expanding the max number of XBC node, changing the > > 'data' type to uint32_t may not have much impact on memory consumption point > > of view, because it may increase only 20% of memory, but expanding the > > MAX_XBC_NODE always increases more than double. > > > > Thus, if we can accept increasing the number of node, it should be OK to > > change the 'data' type. > > That means from DCC point of view only increasing the max nodes is > enough as increasing the data size is unrelated to increasing the max nodes? Yes, if it is less than 32KB, you just need to increase the XBC_NODE_MAX. But if you think the size of bootconfig, we have to change the type of xbc_node::data field. Can you check the DCC also need to expand the size of bootconfig limitation? Thank you! > > > > > BTW, I think now we don't need the ' __attribute__ ((__packed__))' for > > struct xbc_node. It was packed for reducing the size of array and able to > > pass 'compiled' bootconfig, but now it is just passed as a text data for > > safety. > > > > > Thank you, > > > >> > >> > >>> > >>>> > >>>> Signed-off-by: Souradeep Chowdhury > >>>> --- > >>>> include/linux/bootconfig.h | 6 +++--- > >>>> 1 file changed, 3 insertions(+), 3 deletions(-) > >>>> > >>>> diff --git a/include/linux/bootconfig.h b/include/linux/bootconfig.h > >>>> index 1611f9d..64d233b 100644 > >>>> --- a/include/linux/bootconfig.h > >>>> +++ b/include/linux/bootconfig.h > >>>> @@ -55,11 +55,11 @@ struct xbc_node { > >>>> } __attribute__ ((__packed__)); > >>>> > >>>> #define XBC_KEY 0 > >>>> -#define XBC_VALUE (1 << 15) > >>>> -/* Maximum size of boot config is 32KB - 1 */ > >>>> +#define XBC_VALUE (1 << 18) > >>>> +/* Maximum size of boot config is 256KB - 1 */ > >>>> #define XBC_DATA_MAX (XBC_VALUE - 1) > >>>> > >>>> -#define XBC_NODE_MAX 1024 > >>>> +#define XBC_NODE_MAX 8192 > >>>> #define XBC_KEYLEN_MAX 256 > >>>> #define XBC_DEPTH_MAX 16 > >>>> > >>>> -- > >>>> 2.7.4 > >>>> > >>> > >>> > > > > -- Masami Hiramatsu (Google)