From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fgw20-7.mail.saunalahti.fi (fgw20-7.mail.saunalahti.fi [62.142.5.81]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DA47B1F4E59 for ; Tue, 22 Apr 2025 06:38:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=62.142.5.81 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745303903; cv=none; b=Fb0j/wjlVPoJisnd4pbZyWkIwaPmQy5xpdgIjTzP8zpxwd34FHrYr3k3ZBqw74j3DnXCIVMyaO2kEqXLqdmIheI/N1TVOdLdZkH1kKr92Isl3U0aYeIV919kIenKGYtLzlMpxHtIGxdz8oSKbmtnC6qgpVreKjbr95Ry3vyvSUs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745303903; c=relaxed/simple; bh=7usx94h/DwkKANbRL3I4CcV2ppwSaJp7Xo547IrqQns=; h=From:Date:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=cV16EKFi7KV006VWJGiaL8rJi7GjcyK1EOusZ9ZfL1WDdvqB+Xwq/aMiTGVlIlblqv/JsdhkL85PxpxtfvfXAfFm1bzWm7XPRyPhm8XQuZ+w1psBvwMl/2ETL8nva0G6OAl0oFjWq4uliBXBLM4gzGyvFQWpTTix17Jq7x+YwS0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com; spf=fail smtp.mailfrom=gmail.com; arc=none smtp.client-ip=62.142.5.81 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=gmail.com Received: from localhost (88-113-26-232.elisa-laajakaista.fi [88.113.26.232]) by fgw23.mail.saunalahti.fi (Halon) with ESMTP id 607958c7-1f44-11f0-8efd-005056bdfda7; Tue, 22 Apr 2025 09:38:18 +0300 (EEST) From: Andy Shevchenko Date: Tue, 22 Apr 2025 09:38:18 +0300 To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Andy Shevchenko , Arnd Bergmann , Borislav Petkov , Juergen Gross , "H . Peter Anvin" , Kees Cook , Linus Torvalds , Mike Rapoport , Paul Menzel , Peter Zijlstra , Thomas Gleixner , David Woodhouse Subject: Re: [PATCH 07/29] x86/boot/e820: Print out sizes of E820 memory ranges Message-ID: References: <20250421185210.3372306-1-mingo@kernel.org> <20250421185210.3372306-8-mingo@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250421185210.3372306-8-mingo@kernel.org> Mon, Apr 21, 2025 at 08:51:47PM +0200, Ingo Molnar kirjoitti: > Before: > > BIOS-provided physical RAM map: > BIOS-e820: [mem 0x0000000000000000-0x000000000009fbff] usable > BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff] reserved > BIOS-e820: [mem 0x00000000000f0000-0x00000000000fffff] reserved > BIOS-e820: [mem 0x0000000000100000-0x000000007ffdbfff] usable > BIOS-e820: [mem 0x000000007ffdc000-0x000000007fffffff] reserved > BIOS-e820: [mem 0x00000000b0000000-0x00000000bfffffff] reserved > BIOS-e820: [mem 0x00000000fed1c000-0x00000000fed1ffff] reserved > BIOS-e820: [mem 0x00000000feffc000-0x00000000feffffff] reserved > BIOS-e820: [mem 0x00000000fffc0000-0x00000000ffffffff] reserved > BIOS-e820: [mem 0x000000fd00000000-0x000000ffffffffff] reserved > > After: > > BIOS-provided physical RAM map: > BIOS-e820: [mem 0x0000000000000000-0x000000000009fbff] 639 KB kernel usable RAM > BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff] 1 KB reserved > BIOS-e820: [gap 0x00000000000a0000-0x00000000000effff] 320 KB ... > BIOS-e820: [mem 0x00000000000f0000-0x00000000000fffff] 64 KB reserved > BIOS-e820: [mem 0x0000000000100000-0x000000007ffdbfff] 1.9 GB kernel usable RAM > BIOS-e820: [mem 0x000000007ffdc000-0x000000007fffffff] 144 KB reserved > BIOS-e820: [gap 0x0000000080000000-0x00000000afffffff] 768 MB ... > BIOS-e820: [mem 0x00000000b0000000-0x00000000bfffffff] 256 MB reserved > BIOS-e820: [gap 0x00000000c0000000-0x00000000fed1bfff] 1005.1 MB ... > BIOS-e820: [mem 0x00000000fed1c000-0x00000000fed1ffff] 16 KB reserved > BIOS-e820: [gap 0x00000000fed20000-0x00000000feffbfff] 2.8 MB ... > BIOS-e820: [mem 0x00000000feffc000-0x00000000feffffff] 16 KB reserved > BIOS-e820: [gap 0x00000000ff000000-0x00000000fffbffff] 15.7 MB ... > BIOS-e820: [mem 0x00000000fffc0000-0x00000000ffffffff] 256 KB reserved > BIOS-e820: [gap 0x0000000100000000-0x000000fcffffffff] 1008 GB ... > BIOS-e820: [mem 0x000000fd00000000-0x000000ffffffffff] 12 GB reserved > > Note how a 1-digit precision field is printed out if a range is > fractional in its largest-enclosing natural size unit. > > So the "256 MB" and "12 GB" fields above denote exactly 256 MB and > 12 GB regions, while "1.9 GB" signals the region's fractional nature > and it being just below 2GB. > > Printing E820 maps with such details visualizes 'weird' ranges > at a glance, and gives users a better understanding of how > large the various ranges are, without having to perform hexadecimal > subtraction in their minds. ... > +/* > + * Print out the size of a E820 region, in human-readable > + * fashion, going from KB, MB, GB to TB units. > + * > + * Print out fractional sizes with a single digit of precision. > + */ > +static void e820_print_size(u64 size) > +{ > + if (size < SZ_1M) { > + if (size & (SZ_1K-1)) > + pr_cont(" %4llu.%01llu KB", size/SZ_1K, 10*(size & (SZ_1K-1))/SZ_1K); > + else > + pr_cont(" %4llu KB", size/SZ_1K); I would add some spaces here and there for the sake of readability. > + return; > + } > + if (size < SZ_1G) { Can be written in one line as } else if (...) { Ditto for the rest. > + if (size & (SZ_1M-1)) > + pr_cont(" %4llu.%01llu MB", size/SZ_1M, 10*(size & (SZ_1M-1))/SZ_1M); > + else > + pr_cont(" %4llu MB", size/SZ_1M); > + return; > + } > + if (size < SZ_1T) { > + if (size & (SZ_1G-1)) > + pr_cont(" %4llu.%01llu GB", size/SZ_1G, 10*(size & (SZ_1G-1))/SZ_1G); > + else > + pr_cont(" %4llu GB", size/SZ_1G); > + return; > + } > + if (size & (SZ_1T-1)) > + pr_cont(" %4llu.%01llu TB", size/SZ_1T, 10*(size & (SZ_1T-1))/SZ_1T); > + else > + pr_cont(" %4llu TB", size/SZ_1T); > +} Don't you want to use string_helpers.h provided API? string_get_size(). -- With Best Regards, Andy Shevchenko