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 lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 86FEAC433F5 for ; Tue, 10 May 2022 16:19:01 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.325873.548639 (Exim 4.92) (envelope-from ) id 1noSZV-0004aO-U1; Tue, 10 May 2022 16:18:49 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 325873.548639; Tue, 10 May 2022 16:18:49 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1noSZV-0004aH-RD; Tue, 10 May 2022 16:18:49 +0000 Received: by outflank-mailman (input) for mailman id 325873; Tue, 10 May 2022 16:18:48 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1noSZU-0004a3-9M for xen-devel@lists.xenproject.org; Tue, 10 May 2022 16:18:48 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1noSZT-0001ZM-Ig; Tue, 10 May 2022 16:18:47 +0000 Received: from [54.239.6.189] (helo=[192.168.24.150]) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1noSZT-0000gK-CC; Tue, 10 May 2022 16:18:47 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:From: References:Cc:To:Subject:MIME-Version:Date:Message-ID; bh=5hIBuWjHB89ohdv+iWOwRiZQUYeICQW1Fi3o0A9eY8g=; b=cdTP4QXoCa+r/HvkPRFizRNyb0 qHjynnoiGE8jYcbFtZv9gzDL6G7Sj1GpIu57YmTE0rx1L/jkd1hjnP62F/5ZdAJIF30XyXvGC1DtT 1bDIOzMY6ot2gsv/SBoKinY4CsOile9S8BZF4x4bD4YwyCeXNHkHOd7QeA0YOXq2liZQ=; Message-ID: Date: Tue, 10 May 2022 17:18:44 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Subject: Re: [PATCH v3 1/6] xen: implement byteswap To: =?UTF-8?B?TGluIExpdSDvvIjliJjmnpfvvIk=?= , "xen-devel@lists.xenproject.org" Cc: Stefano Stabellini , Bertrand Marquis , Volodymyr Babchuk , Andrew Cooper , George Dunlap , Jan Beulich , Wei Liu , Roger Pau Monne References: <2699787cd4ba1d71448bbcdf190d927e180e80b9.1652170719.git.lin.liu@citrix.com> <11269227-ba07-b2b1-c2ef-ea6309980f67@xen.org> From: Julien Grall In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 10/05/2022 13:10, Lin Liu （刘林） wrote: > On 10/05/2022 11:15, Lin Liu wrote: >> swab() is massively over complicated and can be simplified by builtins. > > NIT: "by builtins" -> "by re-implementing using compiler builtins". > >> The compilers provide builtin function to swap bytes. >> * gcc: https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgcc.gnu.org%2Fonlinedocs%2Fgcc%2FOther-Builtins.html&data=05%7C01%7Clin.liu%40citrix.com%7Ce0b3d98d7f8d47b8fe8708da3275afcd%7C335836de42ef43a2b145348c2ee9ca5b%7C0%7C0%7C637877778294067911%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=HDTF1LDJcD2PLSCuM%2FjIz%2FWGf1CrYk0e%2FLox22%2FXnvQ%3D&reserved=0 >> * clang: https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fclang.llvm.org%2Fdocs%2FLanguageExtensions.html&data=05%7C01%7Clin.liu%40citrix.com%7Ce0b3d98d7f8d47b8fe8708da3275afcd%7C335836de42ef43a2b145348c2ee9ca5b%7C0%7C0%7C637877778294067911%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=EvWcLMi2vtT9haQVo%2F9uXmjBh2zVLUzZAgU57i%2FFMNo%3D&reserved=0 >> This patch simplify swab() with builtins and fallback for old compilers. >> >> Signed-off-by: Lin Liu >> --- >> Cc: Stefano Stabellini >> Cc: Julien Grall >> Cc: Bertrand Marquis >> Cc: Volodymyr Babchuk >> Cc: Andrew Cooper >> Cc: George Dunlap >> Cc: Jan Beulich >> Cc: Wei Liu >> Cc: "Roger Pau Monné" >> Changes in v3: >> - Check __has_builtin instead of GNUC version >> >> Changes in v2: >> - Add fallback for compilers without __builtin_bswap >> - Implement with plain C instead of macros >> --- >> xen/arch/arm/include/asm/byteorder.h | 14 ++----- >> xen/arch/x86/include/asm/byteorder.h | 34 ++--------------- >> xen/include/xen/byteorder.h | 56 ++++++++++++++++++++++++++++ >> xen/include/xen/byteswap.h | 44 ++++++++++++++++++++++ >> xen/include/xen/compiler.h | 12 ++++++ >> 5 files changed, 120 insertions(+), 40 deletions(-) >> create mode 100644 xen/include/xen/byteorder.h >> create mode 100644 xen/include/xen/byteswap.h >> >> diff --git a/xen/arch/arm/include/asm/byteorder.h b/xen/arch/arm/include/asm/byteorder.h >> index 9c712c4788..622eeaba07 100644 >> --- a/xen/arch/arm/include/asm/byteorder.h >> +++ b/xen/arch/arm/include/asm/byteorder.h >> @@ -1,16 +1,10 @@ >> #ifndef __ASM_ARM_BYTEORDER_H__ >> #define __ASM_ARM_BYTEORDER_H__ >> >> -#define __BYTEORDER_HAS_U64__ >> +#ifndef __BYTE_ORDER__ >> + #define __BYTE_ORDER__ __ORDER_LITTLE_ENDIAN__ >> +#endif >> >> -#include >> +#include >> >> #endif /* __ASM_ARM_BYTEORDER_H__ */ >> -/* >> - * Local variables: >> - * mode: C >> - * c-file-style: "BSD" >> - * c-basic-offset: 4 >> - * indent-tabs-mode: nil >> - * End: >> - */ > >>> This change looks unrelated to this patch. Can you explain it? > > Do you mean following code block? Yes, it is unrelated, I removed it as I found some files does not include such field. So in general we try to avoid unrelated change within a same patch. In this case, the emacs magic should be present in the files rather than the other way around. Cheers, -- Julien Grall