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