firewire: fw-ohci: add option for remote debugging (080de8c2) · Commits · 戴 / test

Documentation/debugging-via-ohci1394.txt

+10 −6

Original line number	Diff line number	Diff line
		@@ -41,15 +41,19 @@ to a working state and enables physical DMA by default for all remote nodes.
		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
		-----

+9 −0

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		@@ -1097,6 +1097,11 @@ static void bus_reset_tasklet(unsigned long data)
		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_cancel_packet(struct fw_card card, struct fw_packet packet)
		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 @@ ohci_enable_phys_dma(struct fw_card *card, int node_id, int generation)
		out:
		spin_unlock_irqrestore(&ohci->lock, flags);
		return retval;
		#endif /* CONFIG_FIREWIRE_OHCI_REMOTE_DMA */
		}

		static u64

+12 −1

Original line number	Diff line number	Diff line
		@@ -593,7 +593,7 @@ config LATENCYTOP
		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 @@ config PROVIDE_OHCI1394_DMA_INIT

		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"