linux/arch/mips/Kconfig.debug
Paul Burton 609cf6f229 MIPS: CPS: Early debug using an ns16550-compatible UART
Provide support for outputting early debug information, in the form of
various register values should an exception occur, during the early
bringup of secondary cores. This code requires an ns16550-compatible
UART accessible from the secondary core, and is written in assembly due
to the environment in which such early exceptions occur where way may
not have a stack, be coherent or even have initialised caches.

[ralf@linux-mips.org: Fix merge conflict.]

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: Andrew Bresticker <abrestic@chromium.org>
Cc: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: linux-kernel@vger.kernel.org
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/11202/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2015-11-11 08:34:25 +01:00

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menu "Kernel hacking"
config TRACE_IRQFLAGS_SUPPORT
bool
default y
source "lib/Kconfig.debug"
config EARLY_PRINTK
bool "Early printk" if EXPERT
depends on SYS_HAS_EARLY_PRINTK
default y
help
This option enables special console drivers which allow the kernel
to print messages very early in the bootup process.
This is useful for kernel debugging when your machine crashes very
early before the console code is initialized. For normal operation,
it is not recommended because it looks ugly on some machines and
doesn't cooperate with an X server. You should normally say N here,
unless you want to debug such a crash.
config EARLY_PRINTK_8250
bool
depends on EARLY_PRINTK && USE_GENERIC_EARLY_PRINTK_8250
default y
help
"8250/16550 and compatible serial early printk driver"
If you say Y here, it will be possible to use a 8250/16550 serial
port as the boot console.
config USE_GENERIC_EARLY_PRINTK_8250
bool
config CMDLINE_BOOL
bool "Built-in kernel command line"
default n
help
For most systems, it is firmware or second stage bootloader that
by default specifies the kernel command line options. However,
it might be necessary or advantageous to either override the
default kernel command line or add a few extra options to it.
For such cases, this option allows you to hardcode your own
command line options directly into the kernel. For that, you
should choose 'Y' here, and fill in the extra boot arguments
in CONFIG_CMDLINE.
The built-in options will be concatenated to the default command
line if CMDLINE_OVERRIDE is set to 'N'. Otherwise, the default
command line will be ignored and replaced by the built-in string.
Most MIPS systems will normally expect 'N' here and rely upon
the command line from the firmware or the second-stage bootloader.
config CMDLINE
string "Default kernel command string"
depends on CMDLINE_BOOL
default ""
help
On some platforms, there is currently no way for the boot loader to
pass arguments to the kernel. For these platforms, and for the cases
when you want to add some extra options to the command line or ignore
the default command line, you can supply some command-line options at
build time by entering them here. In other cases you can specify
kernel args so that you don't have to set them up in board prom
initialization routines.
For more information, see the CMDLINE_BOOL and CMDLINE_OVERRIDE
options.
config CMDLINE_OVERRIDE
bool "Built-in command line overrides firmware arguments"
default n
depends on CMDLINE_BOOL
help
By setting this option to 'Y' you will have your kernel ignore
command line arguments from firmware or second stage bootloader.
Instead, the built-in command line will be used exclusively.
Normally, you will choose 'N' here.
config SB1XXX_CORELIS
bool "Corelis Debugger"
depends on SIBYTE_SB1xxx_SOC
select DEBUG_INFO
help
Select compile flags that produce code that can be processed by the
Corelis mksym utility and UDB Emulator.
config DEBUG_ZBOOT
bool "Enable compressed kernel support debugging"
depends on DEBUG_KERNEL && SYS_SUPPORTS_ZBOOT
default n
help
If you want to add compressed kernel support to a new board, and the
board supports uart16550 compatible serial port, please select
SYS_SUPPORTS_ZBOOT_UART16550 for your board and enable this option to
debug it.
If your board doesn't support uart16550 compatible serial port, you
can try to select SYS_SUPPORTS_ZBOOT and use the other methods to
debug it. for example, add a new serial port support just as
arch/mips/boot/compressed/uart-16550.c does.
After the compressed kernel support works, please disable this option
to reduce the kernel image size and speed up the booting procedure a
little.
config SPINLOCK_TEST
bool "Enable spinlock timing tests in debugfs"
depends on DEBUG_FS
default n
help
Add several files to the debugfs to test spinlock speed.
if CPU_MIPSR6
choice
prompt "Compact branch policy"
default MIPS_COMPACT_BRANCHES_OPTIMAL
config MIPS_COMPACT_BRANCHES_NEVER
bool "Never (force delay slot branches)"
help
Pass the -mcompact-branches=never flag to the compiler in order to
force it to always emit branches with delay slots, and make no use
of the compact branch instructions introduced by MIPSr6. This is
useful if you suspect there may be an issue with compact branches in
either the compiler or the CPU.
config MIPS_COMPACT_BRANCHES_OPTIMAL
bool "Optimal (use where beneficial)"
help
Pass the -mcompact-branches=optimal flag to the compiler in order for
it to make use of compact branch instructions where it deems them
beneficial, and use branches with delay slots elsewhere. This is the
default compiler behaviour, and should be used unless you have a
reason to choose otherwise.
config MIPS_COMPACT_BRANCHES_ALWAYS
bool "Always (force compact branches)"
help
Pass the -mcompact-branches=always flag to the compiler in order to
force it to always emit compact branches, making no use of branch
instructions with delay slots. This can result in more compact code
which may be beneficial in some scenarios.
endchoice
endif # CPU_MIPSR6
config SCACHE_DEBUGFS
bool "L2 cache debugfs entries"
depends on DEBUG_FS
help
Enable this to allow parts of the L2 cache configuration, such as
whether or not prefetching is enabled, to be exposed to userland
via debugfs.
If unsure, say N.
menuconfig MIPS_CPS_NS16550
bool "CPS SMP NS16550 UART output"
depends on MIPS_CPS
help
Output debug information via an ns16550 compatible UART if exceptions
occur early in the boot process of a secondary core.
if MIPS_CPS_NS16550
config MIPS_CPS_NS16550_BASE
hex "UART Base Address"
default 0x1b0003f8 if MIPS_MALTA
help
The base address of the ns16550 compatible UART on which to output
debug information from the early stages of core startup.
config MIPS_CPS_NS16550_SHIFT
int "UART Register Shift"
default 0 if MIPS_MALTA
help
The number of bits to shift ns16550 register indices by in order to
form their addresses. That is, log base 2 of the span between
adjacent ns16550 registers in the system.
endif # MIPS_CPS_NS16550
endmenu