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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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2475ff9d2c
This patch adds support for "earlyprintk=" parameter on the kernel command line. The format is: earlyprintk=<name>[,<addr>][,<options>] where <name> is the name of the (UART) device, e.g. "pl011", <addr> is the I/O address. The <options> aren't currently used. The mapping of the earlyprintk device is done very early during kernel boot and there are restrictions on which functions it can call. A special early_io_map() function is added which creates the mapping from the pre-defined EARLY_IOBASE to the device I/O address passed via the kernel parameter. The pgd entry corresponding to EARLY_IOBASE is pre-populated in head.S during kernel boot. Only PL011 is currently supported and it is assumed that the interface is already initialised by the boot loader before the kernel is started. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Arnd Bergmann <arnd@arndb.de>
36 lines
1.1 KiB
Text
36 lines
1.1 KiB
Text
menu "Kernel hacking"
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source "lib/Kconfig.debug"
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config FRAME_POINTER
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bool
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default y
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config DEBUG_ERRORS
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bool "Verbose kernel error messages"
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depends on DEBUG_KERNEL
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help
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This option controls verbose debugging information which can be
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printed when the kernel detects an internal error. This debugging
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information is useful to kernel hackers when tracking down problems,
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but mostly meaningless to other people. It's safe to say Y unless
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you are concerned with the code size or don't want to see these
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messages.
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config DEBUG_STACK_USAGE
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bool "Enable stack utilization instrumentation"
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depends on DEBUG_KERNEL
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help
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Enables the display of the minimum amount of free stack which each
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task has ever had available in the sysrq-T output.
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config EARLY_PRINTK
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bool "Early printk support"
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default y
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help
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Say Y here if you want to have an early console using the
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earlyprintk=<name>[,<addr>][,<options>] kernel parameter. It
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is assumed that the early console device has been initialised
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by the boot loader prior to starting the Linux kernel.
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endmenu
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