+config PROVIDE_OHCI1394_DMA_INIT
+ 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
+ on boot and the crashing machine has a FireWire port, you can use
+ this feature to remotely access the memory of the crashed machine
+ over FireWire. This employs remote DMA as part of the OHCI1394
+ specification which is now the standard for FireWire controllers.
+
+ With remote DMA, you can monitor the printk buffer remotely using
+ firescope and access all memory below 4GB using fireproxy from gdb.
+ Even controlling a kernel debugger is possible using remote DMA.
+
+ Usage:
+
+ If ohci1394_dma=early is used as boot parameter, it will initialize
+ all OHCI1394 controllers which are found in the PCI config space.
+
+ As all changes to the FireWire bus such as enabling and disabling
+ devices cause a bus reset and thereby disable remote DMA for all
+ devices, be sure to have the cable plugged and FireWire enabled on
+ the debugging host before booting the debug target for debugging.
+
+ This code (~1k) is freed after boot. By then, the firewire stack
+ in charge of the OHCI-1394 controllers should be used instead.
+
+ See Documentation/debugging-via-ohci1394.txt for more information.
+
+config DMA_API_DEBUG
+ bool "Enable debugging of DMA-API usage"
+ depends on HAVE_DMA_API_DEBUG
+ help
+ Enable this option to debug the use of the DMA API by device drivers.
+ With this option you will be able to detect common bugs in device
+ drivers like double-freeing of DMA mappings or freeing mappings that
+ were never allocated.
+
+ This also attempts to catch cases where a page owned by DMA is
+ accessed by the cpu in a way that could cause data corruption. For
+ example, this enables cow_user_page() to check that the source page is
+ not undergoing DMA.
+
+ This option causes a performance degradation. Use only if you want to
+ debug device drivers and dma interactions.
+
+ If unsure, say N.
+