kernel-ark/arch/i386/Kconfig.debug
Rusty Russell 139ec7c416 [PATCH] paravirt: Patch inline replacements for paravirt intercepts
It turns out that the most called ops, by several orders of magnitude,
are the interrupt manipulation ops.  These are obvious candidates for
patching, so mark them up and create infrastructure for it.

The method used is that the ops structure has a patch function, which
is called for each place which needs to be patched: this returns a
number of instructions (the rest are NOP-padded).

Usually we can spare a register (%eax) for the binary patched code to
use, but in a couple of critical places in entry.S we can't: we make
the clobbers explicit at the call site, and manually clobber the
allowed registers in debug mode as an extra check.

And:

Don't abuse CONFIG_DEBUG_KERNEL, add CONFIG_DEBUG_PARAVIRT.

And:

AK:  Fix warnings in x86-64 alternative.c build

And:

AK: Fix compilation with defconfig

And:

^From: Andrew Morton <akpm@osdl.org>

Some binutlises still like to emit references to __stop_parainstructions and
__start_parainstructions.

And:

AK: Fix warnings about unused variables when PARAVIRT is disabled.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Zachary Amsden <zach@vmware.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
2006-12-07 02:14:08 +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 EMBEDDED && DEBUG_KERNEL
default y
help
Write kernel log output directly into the VGA buffer or to a serial
port.
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 and doesn't cooperate
with klogd/syslogd or the X server. You should normally N here,
unless you want to debug such a crash.
config DEBUG_STACKOVERFLOW
bool "Check for stack overflows"
depends on DEBUG_KERNEL
help
This option will cause messages to be printed if free stack space
drops below a certain limit.
config DEBUG_STACK_USAGE
bool "Stack utilization instrumentation"
depends on DEBUG_KERNEL
help
Enables the display of the minimum amount of free stack which each
task has ever had available in the sysrq-T and sysrq-P debug output.
This option will slow down process creation somewhat.
comment "Page alloc debug is incompatible with Software Suspend on i386"
depends on DEBUG_KERNEL && SOFTWARE_SUSPEND
config DEBUG_PAGEALLOC
bool "Debug page memory allocations"
depends on DEBUG_KERNEL && !SOFTWARE_SUSPEND && !HUGETLBFS
help
Unmap pages from the kernel linear mapping after free_pages().
This results in a large slowdown, but helps to find certain types
of memory corruptions.
config DEBUG_RODATA
bool "Write protect kernel read-only data structures"
depends on DEBUG_KERNEL
help
Mark the kernel read-only data as write-protected in the pagetables,
in order to catch accidental (and incorrect) writes to such const
data. This option may have a slight performance impact because a
portion of the kernel code won't be covered by a 2MB TLB anymore.
If in doubt, say "N".
config 4KSTACKS
bool "Use 4Kb for kernel stacks instead of 8Kb"
depends on DEBUG_KERNEL
help
If you say Y here the kernel will use a 4Kb stacksize for the
kernel stack attached to each process/thread. This facilitates
running more threads on a system and also reduces the pressure
on the VM subsystem for higher order allocations. This option
will also use IRQ stacks to compensate for the reduced stackspace.
config X86_FIND_SMP_CONFIG
bool
depends on X86_LOCAL_APIC || X86_VOYAGER
default y
config X86_MPPARSE
bool
depends on X86_LOCAL_APIC && !X86_VISWS
default y
config DOUBLEFAULT
default y
bool "Enable doublefault exception handler" if EMBEDDED
help
This option allows trapping of rare doublefault exceptions that
would otherwise cause a system to silently reboot. Disabling this
option saves about 4k and might cause you much additional grey
hair.
config DEBUG_PARAVIRT
bool "Enable some paravirtualization debugging"
default y
depends on PARAVIRT && DEBUG_KERNEL
help
Currently deliberately clobbers regs which are allowed to be
clobbered in inlined paravirt hooks, even in native mode.
If turning this off solves a problem, then DISABLE_INTERRUPTS() or
ENABLE_INTERRUPTS() is lying about what registers can be clobbered.
endmenu