On 05/04/2015 05:58 PM, Robert Schwebel wrote: > On Mon, May 04, 2015 at 05:27:35PM -0400, Peter Hurley wrote: >> As I understand you, >> >> 1. you have CONFIG_SERIAL_EARLYCON=y >> 2. but you don't specify an earlycon >> 3. so no earlycon starts. >> 4. your command line includes "console=ttyAMA0,115200n8" >> 5. and a console starts on that port (yes?) >> >> I don't see a regression here from any previous kernel; this is exactly >> the same behavior as before, so what is broken? > > It outputs a warning message "no match" because it assumes that > "ttyAMA0" (specified in the console= entry on the kernel commandline) > matches with "pl011", coming from OF_EARLYCON_DECLARE for the serial > driver. > > I don't understand how this is supposed to work: it will *never* match, > right? > > You say it is a diagnostics message that indicates a misspelling. > I fail to see what is misspelled, so what does it diagnose? Ok, so this is only about the diagnostic message, and not about some other failure. I don't typically describe harmless diagnostics that didn't appear before as "broken", so I was having trouble believing what I was reading. Now that I understand that this is _only_ about a diagnostic message that didn't appear in previous kernels, I will direct to what I have written previously multiple times. Further, I would ask how _you_ would programmatically distinguish misspellings amongst the following console strings? console=pl012,... console=_pl011,... console=pl,... console=ttyAMA0,... Regards, Peter Hurley >>> In order to let you better understand the setup here: My AM335x device >>> (same CPU as on BeagleBone) is a headless embedded system, the only >>> input/output device it has is a serial port. No display, no touch. For >>> development, a pretty similar system is simulated in QEMU, with >>> vexpress. >>> >>> Until recently, specifying "console=ttyAMA0" was the correct way to get >>> the kernel + userspace output out of that serial line. On ARM, there was >>> no "early" mechanism, only early_printk. >>> >>> I wouldn't mind if your citation from kernel-parameters above was true >>> and I could get an (early and non-early) serial console with a unified >>> "console=ttyAMA0". >>> >>> However, it doesn't work, as "ttyAMA0" doesn't match "pl011". >> >> The AM335x does not have a AMBA pl011 port, so "console=ttyAMA0,..." has no >> effect on that hardware, and never has. Something else is providing console >> on that setup. Please attach your entire dmesg log for that setup. > > Hardware 1: AM335x > drivers/serial/tty/omap-serial.c > console=ttyO2,115200n8 > > Hardware 2: QEMU/vexpress > drivers/serial/tty/amba-pl011.c > console=ttyAMA0,38400 > > The same kernel runs on both platforms. > > Let's just discuss the 2nd case for now, with ttyAMA0 (which is pl011), > which has earlycon support and registers here: > > http://lxr.free-electrons.com/source/drivers/tty/serial/amba-pl011.c#L2129 > >>> So I'm doing the right thing here, and it doesn't work. >> >> I'm not sure what you mean by "it doesn't work". >> Are you saying that the serial console is not starting? > > The serial console is starting. > > It claims that earlycon has "no match", while the correct serial device > is specified. > > How do you suggest this is supposed to be used in the pl011 case, > without the "diagnostic message" triggering that says "no match"? > > Here is the full serial console log (directed to qemu's stdout): > > ----------8<----------8<----------8<----------8<----------8<---------- > rsc@callisto:OSELAS.BSP-GF$ configs/platform-gf/run > [ 0.000000] Linux version 4.1.0-rc1+ (rsc@callisto) (gcc version 4.8.3 20131111 (prerelease) (OSELAS.Toolchain-2013.12.2 linaro-4.8-2013.11) ) #10 PREEMPT Mon May 4 23:03:27 CEST 2015 > [ 0.000000] earlycon: no match for ttyAMA0,38400n8 > [ 0.000000] Kernel command line: root=/dev/mmcblk0p2 rootfs=ext2 rw mem=1024M console=ttyAMA0,38400n8 loglevel=6 rootwait rootfstype=ext4 PS - If the message really bothers you that much, please feel free to submit a patch to Greg that lowers that message level to pr_info() instead, so it doesn't appear in your logs. I've include an _unsigned_ patch below which does just that. Feel free to modify and submit it to Greg with your Signed-off-by. > [ 0.000000] Virtual kernel memory layout: > [ 0.000000] vector : 0xffff0000 - 0xffff1000 ( 4 kB) > [ 0.000000] fixmap : 0xffc00000 - 0xfff00000 (3072 kB) > [ 0.000000] vmalloc : 0xf0000000 - 0xff000000 ( 240 MB) > [ 0.000000] lowmem : 0xc0000000 - 0xef800000 ( 760 MB) > [ 0.000000] pkmap : 0xbfe00000 - 0xc0000000 ( 2 MB) > [ 0.000000] modules : 0xbf000000 - 0xbfe00000 ( 14 MB) > [ 0.000000] .text : 0xc0008000 - 0xc0674ed4 (6580 kB) > [ 0.000000] .init : 0xc0675000 - 0xc06b2000 ( 244 kB) > [ 0.000000] .data : 0xc06b2000 - 0xc06fd3e8 ( 301 kB) > [ 0.000000] .bss : 0xc0700000 - 0xc073a5d8 ( 234 kB) > [ 0.000000] L2C: platform modifies aux control register: 0x02020000 -> 0x02420000 > [ 0.000000] L2C: DT/platform modifies aux control register: 0x02020000 -> 0x02420000 > [ 0.425170] platform 10000000.sysreg: Error -2 creating of_node link > [ 0.429607] platform basic-mmio-gpio.1.auto: Error -2 creating of_node link > [ 0.429959] platform basic-mmio-gpio.2.auto: Error -2 creating of_node link > [ 0.430561] platform basic-mmio-gpio.3.auto: Error -2 creating of_node link > [ 0.604531] of_amba_device_create(): amba_device_add() failed (-19) for /memory-controller@100e0000 > [ 0.605709] of_amba_device_create(): amba_device_add() failed (-19) for /memory-controller@100e1000 > [ 0.606411] of_amba_device_create(): amba_device_add() failed (-19) for /watchdog@100e5000 > [ 0.620892] of_amba_device_create(): amba_device_add() failed (-19) for /smb/motherboard/iofpga@7,00000000/sysctl@01000 > [ 0.633512] of_amba_device_create(): amba_device_add() failed (-19) for /smb/motherboard/iofpga@7,00000000/wdt@0f000 > [ 0.725997] SCSI subsystem initialized > [ 0.796591] NFS: Registering the id_resolver key type > [ 0.797533] Key type id_resolver registered > [ 0.797758] Key type id_legacy registered > [ 0.998780] Key type dns_resolver registered > [ 1.403497] random: nonblocking pool is initialized > > Welcome to PTXdist / af inventions-GF! > > [ OK ] Created slice Root Slice. > [ OK ] Listening on Journal Socket (/dev/log). > [ OK ] Listening on udev Kernel Socket. > > <...> > > ----------8<----------8<----------8<----------8<----------8<---------- > > rsc > --- >% --- Subject: [PATCH] earlycon: Reduce log message level of "earlycon: no match for ..." --- drivers/tty/serial/earlycon.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c index 5fdc9f3..a7725f6 100644 --- a/drivers/tty/serial/earlycon.c +++ b/drivers/tty/serial/earlycon.c @@ -188,7 +188,7 @@ static int __init param_setup_earlycon(char *buf) err = setup_earlycon(buf); if (err == -ENOENT) { - pr_warn("no match for %s\n", buf); + pr_info("no match for %s\n", buf); err = 0; } else if (err == -EALREADY) { pr_warn("already registered\n"); -- 2.4.0 -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
