path: root/arch/powerpc/Kconfig.debug
diff options
authorBenjamin Herrenschmidt <benh@kernel.crashing.org>2011-05-12 13:46:38 +1000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2011-06-29 17:48:35 +1000
commit4d2bb3f5003617cb42b89faefd0009c505c3abd5 (patch)
tree6c64b00f64d5a3290e89003427cff156c9afa640 /arch/powerpc/Kconfig.debug
parentdd2e356a3dd1fea6d911798044532304c3ef4050 (diff)
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>
Diffstat (limited to 'arch/powerpc/Kconfig.debug')
1 files changed, 15 insertions, 0 deletions
diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug
index e72dcf6a421..067cb848074 100644
--- a/arch/powerpc/Kconfig.debug
+++ b/arch/powerpc/Kconfig.debug
@@ -167,6 +167,13 @@ config PPC_EARLY_DEBUG_LPAR
Select this to enable early debugging for a machine with a HVC
console on vterm 0.
+ 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.
bool "Apple G5"
depends on PPC_PMAC64
@@ -253,6 +260,14 @@ config PPC_EARLY_DEBUG_WSP
+ hex "vterm number to use with early debug HVSI"
+ default "0x30000000"
+ help
+ You probably want 0x30000000 for your first serial port and
+ 0x30000001 for your second one
hex "Low 32 bits of early debug UART physical address"
depends on PPC_EARLY_DEBUG_44x