From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 98CF631A89 for ; Tue, 22 Apr 2025 06:53:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745304805; cv=none; b=iqNcrWy5gOFYvZ9dv88z1OsYALvmu97cQDLJBwSo1RfsPas4/BWAAeo4pXwjlgX0OiCYcNZ2hhH13VZg7kKEkn0XtocqMQRXnBV1p2Ft5N9eEvrMPxvHNyJzw9En+TqrVIm0Zt3pJWUhoEeFp86nM946Jehl6vsS+0QtSoKUt5U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745304805; c=relaxed/simple; bh=ZSfX/9AXP1yp2D+Q5Esr2vYyNpiJAD6vPn3Y+lbhp5Y=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=jz3GpEK0hYcU43UedWjQNXK0zb78xAQ8D7V8aZXRLsszMgdYqesdszE6QFPVDkVc93/RljhhZrAYsUo9VhHGiHlsoGT9cRzvmxRSs8bWwwdwbU429vA5gtzXrjXvzAPatJtfGmT9ard0EzBPki4QcJH1WBh1m6ABc6SFTR9s8Tg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MqHU7ghw; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MqHU7ghw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DD3B5C4CEE9; Tue, 22 Apr 2025 06:53:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1745304805; bh=ZSfX/9AXP1yp2D+Q5Esr2vYyNpiJAD6vPn3Y+lbhp5Y=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MqHU7ghwNXhmfLIg/1S8t4kVC7VSRd0dTuTFIADqCxnBNZ9WovyiXH6+lXjPwkFfM iEpsds2P0XDvN4zKM9zkOXGw7fb5ciiNfmaqXwDJUpnSBHomBUrkeYTpbNKYz/Rkbl OS2f7W6Sdjc2Dbu5WiTvm5rutVvXjYta8Goj9QyTPUJR+eAgucG0THR899qTS6O1w0 kwWNTtIHHtsdIVNP7+4s6HwHEmPmYXYrvEL6EPa7oHi162WmiGdj3gUkg9OFwzXucV JSlwhRyDq3o7FskZtNZR1SQcpbk6koPnGCeiAgJujZbfLoefccLJBCZd/4UclAZeOD tdX37dAPti4WQ== Date: Tue, 22 Apr 2025 09:53:17 +0300 From: Mike Rapoport To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Andy Shevchenko , Arnd Bergmann , Borislav Petkov , Juergen Gross , "H . Peter Anvin" , Kees Cook , Linus Torvalds , 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> On Mon, Apr 21, 2025 at 08:51:47PM +0200, Ingo Molnar wrote: > 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. > > Signed-off-by: Ingo Molnar > Cc: Andy Shevchenko > Cc: Arnd Bergmann > Cc: David Woodhouse > Cc: H. Peter Anvin > Cc: Kees Cook > Cc: Linus Torvalds > Cc: Mike Rapoport (Microsoft) > (cherry picked from commit d1ac6b8718575a7ea2f0a1ff347835a8879df673) > --- > arch/x86/kernel/e820.c | 47 +++++++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 45 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c > index 10bd10bd5672..8ee89962fcbf 100644 > --- a/arch/x86/kernel/e820.c > +++ b/arch/x86/kernel/e820.c > @@ -199,6 +199,41 @@ static void __init e820_print_type(enum e820_type type) > } > } > > +/* > + * 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); > + return; > + } I'd make this a helper, e.g static void __e820_print_size(u64 size, u64 unit, const char *unit_name) { if (size & (unit - 1)) { u64 fraction = 10 * (size & (unit - 1))/unit; pr_cont(" %4llu.%01llu %s", size/unit, fraction, unit_name); } else { pr_cont(" %4llu %s", size/unit, unit_name); } } > + if (size < SZ_1G) { > + 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); > +} > + > static void __init e820__print_table(const char *who) > { > u64 range_end_prev = 0; > @@ -215,14 +250,22 @@ static void __init e820__print_table(const char *who) > if (range_start < range_end_prev) > pr_info("BUG: out of order E820 entry!\n"); > > + /* Print gaps, if any: */ > if (range_start > range_end_prev) { > - pr_info("%s: [gap %#018Lx-%#018Lx]\n", > + u64 gap_size = range_start - range_end_prev; > + > + pr_info("%s: [gap %#018Lx-%#018Lx]", > who, > range_end_prev, > range_start-1); > + > + e820_print_size(gap_size); > + pr_cont(" ...\n"); > } > > - pr_info("%s: [mem %#018Lx-%#018Lx] ", who, range_start, range_end-1); > + /* Print allocated ranges: */ > + pr_info("%s: [mem %#018Lx-%#018Lx]", who, range_start, range_end-1); > + e820_print_size(entry->size); > e820_print_type(entry->type); > pr_cont("\n"); > > -- > 2.45.2 > -- Sincerely yours, Mike.