From: robert.jarzmik@free•fr (Robert Jarzmik)
To: linux-arm-kernel@lists•infradead.org
Subject: ARM, earlyconsole and io mapping
Date: Mon, 30 Mar 2015 14:05:33 +0200 [thread overview]
Message-ID: <87iodivgfm.fsf@free.fr> (raw)
Hi,
I was wondering how the earlyconsole was supposed to work in order to add
support to the pxa architecture. More specifically, I don't understand how the
memory mapping is supposed to be available at the early parameters parsing.
The thing I don't understand is that :
- in kernel initialization, parse_early_param() is called before
machine_desc->map_io()
- as a consequence, the architecture didn't add the vm early mapping for serial
peripheral (which is added in pxa_map_io())
- as a consequence, earlycon_map() will fail to map the serial MMIO
(as in stack showed in [1])
Therefore, are there non-DT earlycon users on the list, and could they tell me
what way they get earlycon support in their arm boards please ?
Cheers.
--
Robert
[1] Call stack
#0 __arm_ioremap_pfn_caller (pfn=262400, offset=0, size=64, mtype=0, caller=0xc041d66c) at arch/arm/mm/ioremap.c:260
#1 0xc0015d34 in __arm_ioremap_caller (phys_addr=<value optimized out>, size=<value optimized out>, mtype=0, caller=<value optimized out>) at arch/arm/mm/ioremap.c:354
#2 0xc0015868 in __arm_ioremap (phys_addr=<value optimized out>, size=<value optimized out>, mtype=<value optimized out>) at arch/arm/mm/ioremap.c:383
#3 0xc041d66c in earlycon_map (buf=0x0, match=0x0, setup=0x40) at drivers/tty/serial/earlycon.c:48
#4 setup_earlycon (buf=0x0, match=0x0, setup=0x40) at drivers/tty/serial/earlycon.c:138
#5 0xc040a52c in do_early_param (param=0xc0424bf6 "earlycon", val=0xc0424bff "pxa,mmio,0x40100000,115200n8", unused=<value optimized out>) at init/main.c:420
#6 0xc00306bc in parse_one (doing=0xc0393668 "early options", args=0xc0424c1b "", params=<value optimized out>, num=<value optimized out>, min_level=0, max_level=0, unknown=0) at kernel/params.c:131
#7 parse_args (doing=0xc0393668 "early options", args=0xc0424c1b "", params=<value optimized out>, num=<value optimized out>, min_level=0, max_level=0, unknown=0) at kernel/params.c:216
#8 0xc040a854 in parse_early_options (cmdline=<value optimized out>) at init/main.c:430
#9 0xc040a890 in parse_early_param () at init/main.c:444
#10 0xc040d950 in setup_arch (cmdline_p=0xc07f3fd4) at arch/arm/kernel/setup.c:922
#11 0xc040a918 in start_kernel () at init/main.c:520
=> Here get_vm_area_caller() will fail in __arm_ioremap_pfn_caller().
next reply other threads:[~2015-03-30 12:05 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-30 12:05 Robert Jarzmik [this message]
2015-03-30 12:11 ` ARM, earlyconsole and io mapping Thomas Petazzoni
2015-03-30 13:25 ` Robert Jarzmik
2015-03-30 23:31 ` Peter Hurley
2015-03-31 9:11 ` Robert Jarzmik
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