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linux-next/arch/powerpc/Kconfig.debug
Benjamin Herrenschmidt 4d2bb3f500 powerpc/pseries: Re-implement HVSI as part of hvc_vio 
On pseries machines, consoles are provided by the hypervisor using
a low level get_chars/put_chars type interface. However, this is
really just a transport to the service processor which implements
them either as "raw" console (networked consoles, HMC, ...) or as
"hvsi" serial ports.

The later is a simple packet protocol on top of the raw character
interface that is supposed to convey additional "serial port" style
semantics. In practice however, all it does is provide a way to
read the CD line and set/clear our DTR line, that's it.

We currently implement the "raw" protocol as an hvc console backend
(/dev/hvcN) and the "hvsi" protocol using a separate tty driver
(/dev/hvsi0).

However this is quite impractical. The arbitrary difference between
the two type of devices has been a major source of user (and distro)
confusion. Additionally, there's an additional mini -hvsi implementation
in the pseries platform code for our low level debug console and early
boot kernel messages, which means code duplication, though that low
level variant is impractical as it's incapable of doing the initial
protocol negociation to establish the link to the FSP.

This essentially replaces the dedicated hvsi driver and the platform
udbg code completely by extending the existing hvc_vio backend used
in "raw" mode so that:

 - It now supports HVSI as well
 - We add support for hvc backend providing tiocm{get,set}
 - It also provides a udbg interface for early debug and boot console

This is overall less code, though this will only be obvious once we
remove the old "hvsi" driver, which is still available for now. When
the old driver is enabled, the new code still kicks in for the low
level udbg console, replacing the old mini implementation in the platform
code, it just doesn't provide the higher level "hvc" interface.

In addition to producing generally simler code, this has several benefits
over our current situation:

 - The user/distro only has to deal with /dev/hvcN for the hypervisor
console, avoiding all sort of confusion that has plagued us in the past

 - The tty, kernel and low level debug console all use the same code
base which supports the full protocol establishment process, thus the
console is now available much earlier than it used to be with the
old HVSI driver. The kernel console works much earlier and udbg is
available much earlier too. Hackers can enable a hard coded very-early
debug console as well that works with HVSI (previously that was only
supported for the "raw" mode).

I've tried to keep the same semantics as hvsi relative to how I react
to things like CD changes, with some subtle differences though:

 - I clear DTR on close if HUPCL is set

 - Current hvsi triggers a hangup if it detects a up->down transition
   on CD (you can still open a console with CD down). My new implementation
   triggers a hangup if the link to the FSP is severed, and severs it upon
   detecting a up->down transition on CD.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2011-06-29 17:48:35 +10:00

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menu "Kernel hacking"
source "lib/Kconfig.debug"
config PPC_DISABLE_WERROR
bool "Don't build arch/powerpc code with -Werror"
default n
help
This option tells the compiler NOT to build the code under
arch/powerpc with the -Werror flag (which means warnings
are treated as errors).
Only enable this if you are hitting a build failure in the
arch/powerpc code caused by a warning, and you don't feel
inclined to fix it.
config PPC_WERROR
bool
depends on !PPC_DISABLE_WERROR
default y
config PRINT_STACK_DEPTH
int "Stack depth to print" if DEBUG_KERNEL
default 64
help
This option allows you to set the stack depth that the kernel
prints in stack traces. This can be useful if your display is
too small and stack traces cause important information to
scroll off the screen.
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 HCALL_STATS
bool "Hypervisor call instrumentation"
depends on PPC_PSERIES && DEBUG_FS && TRACEPOINTS
help
Adds code to keep track of the number of hypervisor calls made and
the amount of time spent in hypervisor calls. Wall time spent in
each call is always calculated, and if available CPU cycles spent
are also calculated. A directory named hcall_inst is added at the
root of the debugfs filesystem. Within the hcall_inst directory
are files that contain CPU specific call statistics.
This option will add a small amount of overhead to all hypervisor
calls.
config PPC_EMULATED_STATS
bool "Emulated instructions tracking"
depends on DEBUG_FS
help
Adds code to keep track of the number of instructions that are
emulated by the in-kernel emulator. Counters for the various classes
of emulated instructions are available under
powerpc/emulated_instructions/ in the root of the debugfs file
system. Optionally (controlled by
powerpc/emulated_instructions/do_warn in debugfs), rate-limited
warnings can be printed to the console when instructions are
emulated.
config CODE_PATCHING_SELFTEST
bool "Run self-tests of the code-patching code."
depends on DEBUG_KERNEL
default n
config FTR_FIXUP_SELFTEST
bool "Run self-tests of the feature-fixup code."
depends on DEBUG_KERNEL
default n
config MSI_BITMAP_SELFTEST
bool "Run self-tests of the MSI bitmap code."
depends on DEBUG_KERNEL
default n
config XMON
bool "Include xmon kernel debugger"
depends on DEBUG_KERNEL
help
Include in-kernel hooks for the xmon kernel monitor/debugger.
Unless you are intending to debug the kernel, say N here.
Make sure to enable also CONFIG_BOOTX_TEXT on Macs. Otherwise
nothing will appear on the screen (xmon writes directly to the
framebuffer memory).
The cmdline option 'xmon' or 'xmon=early' will drop into xmon
very early during boot. 'xmon=on' will just enable the xmon
debugger hooks. 'xmon=off' will disable the debugger hooks
if CONFIG_XMON_DEFAULT is set.
xmon will print a backtrace on the very first invocation.
'xmon=nobt' will disable this autobacktrace.
config XMON_DEFAULT
bool "Enable xmon by default"
depends on XMON
help
xmon is normally disabled unless booted with 'xmon=on'.
Use 'xmon=off' to disable xmon init during runtime.
config XMON_DISASSEMBLY
bool "Include disassembly support in xmon"
depends on XMON
default y
help
Include support for disassembling in xmon. You probably want
to say Y here, unless you're building for a memory-constrained
system.
config DEBUGGER
bool
depends on KGDB || XMON
default y
config VIRQ_DEBUG
bool "Expose hardware/virtual IRQ mapping via debugfs"
depends on DEBUG_FS
help
This option will show the mapping relationship between hardware irq
numbers and virtual irq numbers. The mapping is exposed via debugfs
in the file powerpc/virq_mapping.
If you don't know what this means you don't need it.
config BDI_SWITCH
bool "Include BDI-2000 user context switcher"
depends on DEBUG_KERNEL && PPC32
help
Include in-kernel support for the Abatron BDI2000 debugger.
Unless you are intending to debug the kernel with one of these
machines, say N here.
config BOOTX_TEXT
bool "Support for early boot text console (BootX or OpenFirmware only)"
depends on PPC_OF && PPC_BOOK3S
help
Say Y here to see progress messages from the boot firmware in text
mode. Requires either BootX or Open Firmware.
config PPC_EARLY_DEBUG
bool "Early debugging (dangerous)"
# PPC_EARLY_DEBUG on 440 leaves AS=1 mappings above the TLB high water
# mark, which doesn't work with current 440 KVM.
depends on !KVM
help
Say Y to enable some early debugging facilities that may be available
for your processor/board combination. Those facilities are hacks
intended to debug problems early during boot, this should not be
enabled in a production kernel.
Note that enabling this will also cause the kernel default log level
to be pushed to max automatically very early during boot
choice
prompt "Early debugging console"
depends on PPC_EARLY_DEBUG
help
Use the selected console for early debugging. Careful, if you
enable debugging for the wrong type of machine your kernel
_will not boot_.
config PPC_EARLY_DEBUG_LPAR
bool "LPAR HV Console"
depends on PPC_PSERIES
help
Select this to enable early debugging for a machine with a HVC
console on vterm 0.
config PPC_EARLY_DEBUG_LPAR_HVSI
bool "LPAR HVSI Console"
depends on PPC_PSERIES
help
Select this to enable early debugging for a machine with a HVSI
console on a specified vterm.
config PPC_EARLY_DEBUG_G5
bool "Apple G5"
depends on PPC_PMAC64
help
Select this to enable early debugging for Apple G5 machines.
config PPC_EARLY_DEBUG_RTAS_PANEL
bool "RTAS Panel"
depends on PPC_RTAS
help
Select this to enable early debugging via the RTAS panel.
config PPC_EARLY_DEBUG_RTAS_CONSOLE
bool "RTAS Console"
depends on PPC_RTAS
select UDBG_RTAS_CONSOLE
help
Select this to enable early debugging via the RTAS console.
config PPC_EARLY_DEBUG_MAPLE
bool "Maple real mode"
depends on PPC_MAPLE
help
Select this to enable early debugging for Maple.
config PPC_EARLY_DEBUG_ISERIES
bool "iSeries HV Console"
depends on PPC_ISERIES
help
Select this to enable early debugging for legacy iSeries. You need
to hit "Ctrl-x Ctrl-x" to see the messages on the console.
config PPC_EARLY_DEBUG_PAS_REALMODE
bool "PA Semi real mode"
depends on PPC_PASEMI
help
Select this to enable early debugging for PA Semi.
Output will be on UART0.
config PPC_EARLY_DEBUG_BEAT
bool "Beat HV Console"
depends on PPC_CELLEB
select PPC_UDBG_BEAT
help
Select this to enable early debugging for Celleb with Beat.
config PPC_EARLY_DEBUG_44x
bool "Early serial debugging for IBM/AMCC 44x CPUs"
depends on 44x
help
Select this to enable early debugging for IBM 44x chips via the
inbuilt serial port. If you enable this, ensure you set
PPC_EARLY_DEBUG_44x_PHYSLOW below to suit your target board.
config PPC_EARLY_DEBUG_40x
bool "Early serial debugging for IBM/AMCC 40x CPUs"
depends on 40x
help
Select this to enable early debugging for IBM 40x chips via the
inbuilt serial port. This works on chips with a 16550 compatible
UART. Xilinx chips with uartlite cannot use this option.
config PPC_EARLY_DEBUG_CPM
bool "Early serial debugging for Freescale CPM-based serial ports"
depends on SERIAL_CPM
select PIN_TLB if PPC_8xx
help
Select this to enable early debugging for Freescale chips
using a CPM-based serial port. This assumes that the bootwrapper
has run, and set up the CPM in a particular way.
config PPC_EARLY_DEBUG_USBGECKO
bool "Early debugging through the USB Gecko adapter"
depends on GAMECUBE_COMMON
select USBGECKO_UDBG
help
Select this to enable early debugging for Nintendo GameCube/Wii
consoles via an external USB Gecko adapter.
config PPC_EARLY_DEBUG_WSP
bool "Early debugging via WSP's internal UART"
depends on PPC_WSP
select PPC_UDBG_16550
endchoice
config PPC_EARLY_DEBUG_HVSI_VTERMNO
hex "vterm number to use with early debug HVSI"
depends on PPC_EARLY_DEBUG_LPAR_HVSI
default "0x30000000"
help
You probably want 0x30000000 for your first serial port and
0x30000001 for your second one
config PPC_EARLY_DEBUG_44x_PHYSLOW
hex "Low 32 bits of early debug UART physical address"
depends on PPC_EARLY_DEBUG_44x
default "0x40000200"
help
You probably want 0x40000200 for ebony boards and
0x40000300 for taishan
config PPC_EARLY_DEBUG_44x_PHYSHIGH
hex "EPRN of early debug UART physical address"
depends on PPC_EARLY_DEBUG_44x
default "0x1"
config PPC_EARLY_DEBUG_40x_PHYSADDR
hex "Early debug UART physical address"
depends on PPC_EARLY_DEBUG_40x
default "0xef600300"
config PPC_EARLY_DEBUG_CPM_ADDR
hex "CPM UART early debug transmit descriptor address"
depends on PPC_EARLY_DEBUG_CPM
default "0xfa202008" if PPC_EP88XC
default "0xf0001ff8" if CPM2
default "0xff002008" if CPM1
help
This specifies the address of the transmit descriptor
used for early debug output. Because it is needed before
platform probing is done, all platforms selected must
share the same address.
endmenu
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