Messages in this thread | | | From | Sahara <> | Date | Fri, 29 Aug 2014 14:28:38 +0900 (KST) | Subject | Re: [PATCH] earlyprintk: re-enable earlyprintk calling early_param |
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On Wed, 27 Aug 2014, Thierry Reding wrote:
> On Thu, Aug 14, 2014 at 07:13:36PM +0900, kpark3469@gmail.com wrote: >> From: Sahara <keun-o.park@windriver.com> >> >> Although there are many obs_kernel_param and its names are >> earlyprintk and also EARLY_PRINTK is also enabled, we could not >> see the early_printk output properly until now. This patch >> considers earlycon as well as earlyprintk. >> >> Signed-off-by: Sahara <keun-o.park@windriver.com> >> --- >> init/main.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/init/main.c b/init/main.c >> index bb1aed9..235d248 100644 >> --- a/init/main.c >> +++ b/init/main.c >> @@ -426,7 +426,8 @@ static int __init do_early_param(char *param, char *val, const char *unused) >> for (p = __setup_start; p < __setup_end; p++) { >> if ((p->early && parameq(param, p->str)) || >> (strcmp(param, "console") == 0 && >> - strcmp(p->str, "earlycon") == 0) >> + ((strcmp(p->str, "earlycon") == 0) || >> + (strcmp(p->str, "earlyprintk") == 0))) >> ) { >> if (p->setup_func(val) != 0) >> pr_warn("Malformed early option '%s'\n", param); > > It seems like this patch causes the following warning for me during > boot: > > [ 0.000000] Booting Linux on physical CPU 0x0 > [ 0.000000] Initializing cgroup subsys cpu > [ 0.000000] Initializing cgroup subsys cpuacct > [ 0.000000] Linux version 3.17.0-rc2-next-20140827 (thierry.reding@ulmo) (gcc version 4.9.0 (GCC) ) #18 SMP PREEMPT Wed Aug 27 17:08:12 CEST 2014 > [ 0.000000] CPU: ARMv7 Processor [413fc0f3] revision 3 (ARMv7), cr=10c5387d > [ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, PIPT instruction cache > [ 0.000000] Machine model: NVIDIA Tegra124 Jetson TK1 > [ 0.000000] bootconsole [earlycon0] enabled > [ 0.000000] debug: ignoring loglevel setting. > [ 0.000000] ------------[ cut here ]------------ > [ 0.000000] WARNING: CPU: 0 PID: 0 at /home/thierry.reding/src/kernel/linux-work.git/kernel/printk/printk.c:2402 register_console+0x60/0x37c() > [ 0.000000] console 'earlycon0' already registered > [ 0.000000] Modules linked in: > [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 3.17.0-rc2-next-20140827 #18 > [ 0.000000] [<c0015fec>] (unwind_backtrace) from [<c0011aac>] (show_stack+0x10/0x14) > [ 0.000000] [<c0011aac>] (show_stack) from [<c062b700>] (dump_stack+0x98/0xd8) > [ 0.000000] [<c062b700>] (dump_stack) from [<c0025ba0>] (warn_slowpath_common+0x70/0x8c) > [ 0.000000] [<c0025ba0>] (warn_slowpath_common) from [<c0025bec>] (warn_slowpath_fmt+0x30/0x40) > [ 0.000000] [<c0025bec>] (warn_slowpath_fmt) from [<c00639b8>] (register_console+0x60/0x37c) > [ 0.000000] [<c00639b8>] (register_console) from [<c0883870>] (setup_early_printk+0x20/0x28) > [ 0.000000] [<c0883870>] (setup_early_printk) from [<c087f43c>] (do_early_param+0x6c/0xd0) > [ 0.000000] [<c087f43c>] (do_early_param) from [<c003cba0>] (parse_args+0x238/0x3d0) > [ 0.000000] [<c003cba0>] (parse_args) from [<c087f814>] (parse_early_options+0x38/0x40) > [ 0.000000] [<c087f814>] (parse_early_options) from [<c087f84c>] (parse_early_param+0x30/0x40) > [ 0.000000] [<c087f84c>] (parse_early_param) from [<c088206c>] (setup_arch+0x4b4/0x974) > [ 0.000000] [<c088206c>] (setup_arch) from [<c087f8f8>] (start_kernel+0x98/0x3a8) > [ 0.000000] [<c087f8f8>] (start_kernel) from [<80008074>] (0x80008074) > [ 0.000000] ---[ end trace cb88537fdc8fa200 ]--- > [ 0.000000] cma: Reserved 128 MiB at a7800000 > [ 0.000000] Memory policy: Data cache writealloc > [ 0.000000] On node 0 totalpages: 524032 > [ 0.000000] free_area_init_node: node 0, pgdat c091cc00, node_mem_map e67b7000 > [ 0.000000] Normal zone: 1520 pages used for memmap > [ 0.000000] Normal zone: 0 pages reserved > [ 0.000000] Normal zone: 194560 pages, LIFO batch:31 > [ 0.000000] HighMem zone: 2574 pages used for memmap > [ 0.000000] HighMem zone: 329472 pages, LIFO batch:31 > [ 0.000000] PERCPU: Embedded 8 pages/cpu @e6767000 s8832 r8192 d15744 u32768 > [ 0.000000] pcpu-alloc: s8832 r8192 d15744 u32768 alloc=8*4096 > [ 0.000000] pcpu-alloc: [0] 0 [0] 1 [0] 2 [0] 3 > [ 0.000000] Built 1 zonelists in Zone order, mobility grouping on. Total pages: 522512 > [ 0.000000] Kernel command line: console=ttyS0,115200n8 ignore_loglevel rootwait ro earlyprintk ip=:::::eth0:dhcp root=/dev/nfs nfsroot=192.168.69.100:/srv/nfs/tegra124 drm.debug=0xf cma=128M > > Reverting the patch eliminates the warning. earlyprintk does work fine > for me without this patch. > > Thierry
This warning message is caused by specifying 'earlyprintk' in your command line args. Same problem may happen if you specify 'earlycon' in your command line args and enable CONFIG_SERIAL_EARLYCON with the current code without this patch. I think it's appropriate result letting a developer know that both ways of using earlyprintk are enabled. With current code, although a developer enables CONFIG_EARLY_PRINTK and has "console=" arg in command line args, he/she should specify the 'earlyprintk' in command line args also to see early_printk() outputs. With this patch, simply enabling CONFIG_EARLY_PRINTK and having 'console=' line make you be able to the early_printk().
Nonetheless I want to retract this patch. It's good for ARM, but not good for other architectures such as x86. And, because CONFIG_EARLY_PRINTK is depending on DEBUG_LL in ARM, making a relation with "console=" is absurd. (see strcmp(param, "console") == 0 && strcmp(p->str, "earlyprintk") == 0)
- Sahara
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