Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757251Ab0GMUlK (ORCPT ); Tue, 13 Jul 2010 16:41:10 -0400 Received: from rcsinet10.oracle.com ([148.87.113.121]:32587 "EHLO rcsinet10.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754491Ab0GMUlH (ORCPT ); Tue, 13 Jul 2010 16:41:07 -0400 Message-ID: <4C3CCE05.4090505@kernel.org> Date: Tue, 13 Jul 2010 13:35:17 -0700 From: Yinghai Lu User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.10) Gecko/20100520 SUSE/3.0.5 Thunderbird/3.0.5 MIME-Version: 1.0 To: Pekka Enberg CC: "H. Peter Anvin" , Ingo Molnar , Thomas Gleixner , Andrew Morton , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] x86: Setup early console as early as possible References: <4C3A3B27.7020009@oracle.com> <4C3AD94C.7070807@cs.helsinki.fi> <4C3B38F7.1050400@zytor.com> <4C3B40F3.6070009@kernel.org> <4C3CA5A9.6000607@cs.helsinki.fi> In-Reply-To: <4C3CA5A9.6000607@cs.helsinki.fi> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Source-IP: acsmt354.oracle.com [141.146.40.154] X-Auth-Type: Internal IP X-CT-RefId: str=0001.0A090208.4C3CCF02.0050,ss=1,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5191 Lines: 194 On 07/13/2010 10:43 AM, Pekka Enberg wrote: > Hi Yingahai, > > Yinghai Lu wrote: >> On 07/12/2010 08:47 AM, H. Peter Anvin wrote: >>> On 07/12/2010 01:58 AM, Pekka Enberg wrote: >>>> Hi Yinghai, >>>> >>>> Yinghai Lu wrote: >>>>> Analyze "console=uart8250,io,0x3f8,115200n8" in >>>>> i386_start_kernel/x86_64_start_kernel, >>>>> and call setup_early_serial8250_console() to init early serial >>>>> console. >>>>> >>>>> only can handle io port kind of 8250. because mmio need ioremap. >>>>> >>>>> Signed-off-by: Yinghai Lu >>>> What's the purpose of this patch? Does it make my early boot I/O patch >>>> obsolete? >>>> >>>> Pekka >>> No, they're complementary. Your patch serial-port enables the RM >>> kernel, whereas Yinghai pushes the initialization earlier in the PM >>> kernel. >> >> yes. cover more range. >> >> Can you consider to ask Pekka to anaylze "console=uart8250,io, >> 0x3f8,115200n8" instead? >> >> it looks like we can remove "earlyprintk=ttyS0,115200", or >> "earlyprintk=serial" etc. >> >> earlycon=uart8250 or console=uart8250 should be better than earlyprintk. >> because it is shared between different archs already. > > So just to clarify: I wasn't ignoring your comment here. I simply > followed hpa's recommendation on which I also happen to agree with > completely. ;-) never mind. following patch add that checking. also you missed simple_guess_base(), your patch may have problem with baud rate reading. baud = simple_strtoull(arg + pos, &e, 0); if (baud == 0 || arg + pos == e) baud = DEFAULT_BAUD; and your copied simple_strtoull does not calling simple_guess_base(), so base will 0. so you are always using DEFAULT_BAUD. Thanks Yinghai Lu [PATCH] x86: make boot code to analyze console=uart8250 too So we use console=uart8250,io,0x2f8,115200n all the way Also add back simple_guess_base(), otherwise those simple_strtoull(,,0) are not going to work. Signed-off-by: Yinghai Lu --- arch/x86/boot/string.c | 22 ++++++++++++++++++ arch/x86/boot/tty.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 80 insertions(+), 1 deletion(-) Index: linux-2.6/arch/x86/boot/tty.c =================================================================== --- linux-2.6.orig/arch/x86/boot/tty.c +++ linux-2.6/arch/x86/boot/tty.c @@ -170,7 +170,7 @@ static void early_serial_init(int baud) outb(c & ~DLAB, early_serial_base + LCR); } -void console_init(void) +static int parse_earlyprintk(void) { int baud = DEFAULT_BAUD; char arg[32]; @@ -208,6 +208,63 @@ void console_init(void) baud = DEFAULT_BAUD; } + return baud; +} + +#define BASE_BAUD (1843200/16) +static unsigned int probe_baud(int port) +{ + unsigned char lcr, dll, dlh; + unsigned int quot; + + lcr = inb(port + LCR); + outb(lcr | DLAB, port + LCR); + dll = inb(port + DLL); + dlh = inb(port + DLH); + outb(lcr, port + LCR); + quot = (dlh << 8) | dll; + + return BASE_BAUD / quot; +} + +static int parse_console_uart8250(void) +{ + char optstr[64], *options; + int baud = DEFAULT_BAUD; + + /* + * console=uart8250,io,0x3f8,115200n8 + * need to make sure it is last one console ! + */ + if (cmdline_find_option("console", optstr, sizeof optstr) <= 0) + return baud; + + options = optstr; + + if (!strncmp(options, "uart8250,io,", 12)) + early_serial_base = simple_strtoull(options + 12, &options, 0); + else if (!strncmp(options, "uart,io,", 8)) + early_serial_base = simple_strtoull(options + 8, &options, 0); + else + return baud; + + if (options && (options[0] == ',')) + baud = simple_strtoull(options + 1, &options, 0); + else + baud = probe_baud(early_serial_base); + + return baud; +} + +void console_init(void) +{ + int baud; + + baud = parse_earlyprintk(); + + if (!early_serial_base) + baud = parse_console_uart8250(); + if (early_serial_base != 0) early_serial_init(baud); } Index: linux-2.6/arch/x86/boot/string.c =================================================================== --- linux-2.6.orig/arch/x86/boot/string.c +++ linux-2.6/arch/x86/boot/string.c @@ -68,10 +68,32 @@ unsigned int atou(const char *s) /* Works only for digits and letters, but small and fast */ #define TOLOWER(x) ((x) | 0x20) +static unsigned int simple_guess_base(const char *cp) +{ + if (cp[0] == '0') { + if (TOLOWER(cp[1]) == 'x' && isxdigit(cp[2])) + return 16; + else + return 8; + } else { + return 10; + } +} + +/** + * simple_strtoull - convert a string to an unsigned long long + * @cp: The start of the string + * @endp: A pointer to the end of the parsed string will be placed here + * @base: The number base to use + */ + unsigned long long simple_strtoull(const char *cp, char **endp, unsigned int base) { unsigned long long result = 0; + if (!base) + base = simple_guess_base(cp); + if (base == 16 && cp[0] == '0' && TOLOWER(cp[1]) == 'x') cp += 2; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/