firewire: fw-ohci: add option for remote debugging
This way firewire-ohci can be used for remote debugging like ohci1394.
Version with amendment from Fri, 11 Apr 2008 00:08:08 +0200.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Acked-by: Bernhard Kaindl <bk@suse.de>
diff --git a/Documentation/debugging-via-ohci1394.txt b/Documentation/debugging-via-ohci1394.txt
index c360d4e..59a91e5 100644
--- a/Documentation/debugging-via-ohci1394.txt
+++ b/Documentation/debugging-via-ohci1394.txt
@@ -41,15 +41,19 @@
This can be turned off by ohci1394's module parameter phys_dma=0.
The alternative firewire-ohci driver in drivers/firewire uses filtered physical
-DMA, hence is not yet suitable for remote debugging.
+DMA by default, which is more secure but not suitable for remote debugging.
+Compile the driver with CONFIG_FIREWIRE_OHCI_REMOTE_DMA (Kernel hacking menu:
+Remote debugging over FireWire with firewire-ohci) to get unfiltered physical
+DMA.
-Because ohci1394 depends on the PCI enumeration to be completed, an
-initialization routine which runs pretty early (long before console_init()
-which makes the printk buffer appear on the console can be called) was written.
+Because ohci1394 and firewire-ohci depend on the PCI enumeration to be
+completed, an initialization routine which runs pretty early has been
+implemented for x86. This routine runs long before console_init() can be
+called, i.e. before the printk buffer appears on the console.
To activate it, enable CONFIG_PROVIDE_OHCI1394_DMA_INIT (Kernel hacking menu:
-Provide code for enabling DMA over FireWire early on boot) and pass the
-parameter "ohci1394_dma=early" to the recompiled kernel on boot.
+Remote debugging over FireWire early on boot) and pass the parameter
+"ohci1394_dma=early" to the recompiled kernel on boot.
Tools
-----
diff --git a/drivers/firewire/fw-ohci.c b/drivers/firewire/fw-ohci.c
index 07d6053..5da7c67 100644
--- a/drivers/firewire/fw-ohci.c
+++ b/drivers/firewire/fw-ohci.c
@@ -1097,6 +1097,11 @@
reg_write(ohci, OHCI1394_ConfigROMhdr, ohci->next_header);
}
+#ifdef CONFIG_FIREWIRE_OHCI_REMOTE_DMA
+ reg_write(ohci, OHCI1394_PhyReqFilterHiSet, ~0);
+ reg_write(ohci, OHCI1394_PhyReqFilterLoSet, ~0);
+#endif
+
spin_unlock_irqrestore(&ohci->lock, flags);
if (free_rom)
@@ -1435,6 +1440,9 @@
static int
ohci_enable_phys_dma(struct fw_card *card, int node_id, int generation)
{
+#ifdef CONFIG_FIREWIRE_OHCI_REMOTE_DMA
+ return 0;
+#else
struct fw_ohci *ohci = fw_ohci(card);
unsigned long flags;
int n, retval = 0;
@@ -1466,6 +1474,7 @@
out:
spin_unlock_irqrestore(&ohci->lock, flags);
return retval;
+#endif /* CONFIG_FIREWIRE_OHCI_REMOTE_DMA */
}
static u64
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 0796c1a..78955eb 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -593,7 +593,7 @@
to find out which userspace is blocking on what kernel operations.
config PROVIDE_OHCI1394_DMA_INIT
- bool "Provide code for enabling DMA over FireWire early on boot"
+ bool "Remote debugging over FireWire early on boot"
depends on PCI && X86
help
If you want to debug problems which hang or crash the kernel early
@@ -621,4 +621,15 @@
See Documentation/debugging-via-ohci1394.txt for more information.
+config FIREWIRE_OHCI_REMOTE_DMA
+ bool "Remote debugging over FireWire with firewire-ohci"
+ depends on FIREWIRE_OHCI
+ help
+ This option lets you use the FireWire bus for remote debugging
+ with help of the firewire-ohci driver. It enables unfiltered
+ remote DMA in firewire-ohci.
+ See Documentation/debugging-via-ohci1394.txt for more information.
+
+ If unsure, say N.
+
source "samples/Kconfig"
