Messages in this thread Patch in this message | | | Date | Sat, 18 Jan 2014 16:33:15 +0100 | From | Stefan Richter <> | Subject | [PATCH] firewire: Enable remote DMA above 4 GB |
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This makes all of a machine's memory accessible to remote debugging via FireWire, using the physical response unit (i.e. RDMA) of OHCI-1394 link layer controllers.
This requires actual support by the controller. The only ones currently known to support it are Agere/LSI FW643. Most if not all other OHCI-1394 controllers do not implement the optional Physical Upper Bound register. With them, RDMA will continue to be limited to the lowermost 4 GB.
firewire-ohci's startup message in the kernel log is augmented to tell whether the controller does expose more than 4 GB to RDMA.
While OHCI-1394 allows for a maximum Physical Upper Bound of 0xffff'0000'0000 (near 256 TB), this implementation sets it to 0x8000'0000'0000 (128 TB) in order to avoid interference with applications that require interrupt-served asynchronous request reception at respectively low addresses.
Derived from patch "firewire: Enable physical DMA above 4GB" by Peter Hurley <peter@hurleysoftware.com> from March 27, 2013.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> --- drivers/firewire/core-transaction.c | 6 +++--- drivers/firewire/core.h | 3 +++ drivers/firewire/ohci.c | 8 +++++--- 3 files changed, 11 insertions(+), 6 deletions(-)
--- a/drivers/firewire/core-transaction.c +++ b/drivers/firewire/core-transaction.c @@ -523,11 +523,11 @@ static DEFINE_SPINLOCK(address_handler_l static LIST_HEAD(address_handler_list); const struct fw_address_region fw_high_memory_region = - { .start = 0x000100000000ULL, .end = 0xffffe0000000ULL, }; + { .start = FW_MAX_PHYSICAL_RANGE, .end = 0xffffe0000000ULL, }; EXPORT_SYMBOL(fw_high_memory_region); static const struct fw_address_region low_memory_region = - { .start = 0x000000000000ULL, .end = 0x000100000000ULL, }; + { .start = 0x000000000000ULL, .end = FW_MAX_PHYSICAL_RANGE, }; #if 0 const struct fw_address_region fw_private_region = @@ -1217,7 +1217,7 @@ static void handle_low_memory(struct fw_ } static struct fw_address_handler low_memory = { - .length = 0x000100000000ULL, + .length = FW_MAX_PHYSICAL_RANGE, .address_callback = handle_low_memory, }; --- a/drivers/firewire/core.h +++ b/drivers/firewire/core.h @@ -237,6 +237,9 @@ static inline bool is_next_generation(in #define LOCAL_BUS 0xffc0 +/* arbitrarily chosen maximum range for physical DMA: 128 TB */ +#define FW_MAX_PHYSICAL_RANGE (128ULL << 40) + void fw_core_handle_request(struct fw_card *card, struct fw_packet *request); void fw_core_handle_response(struct fw_card *card, struct fw_packet *packet); int fw_get_response_length(struct fw_request *request); --- a/drivers/firewire/ohci.c +++ b/drivers/firewire/ohci.c @@ -2367,7 +2367,7 @@ static int ohci_enable(struct fw_card *c reg_write(ohci, OHCI1394_FairnessControl, 0); card->priority_budget_implemented = ohci->pri_req_max != 0; - reg_write(ohci, OHCI1394_PhyUpperBound, 0x00010000); + reg_write(ohci, OHCI1394_PhyUpperBound, FW_MAX_PHYSICAL_RANGE >> 16); reg_write(ohci, OHCI1394_IntEventClear, ~0); reg_write(ohci, OHCI1394_IntMaskClear, ~0); @@ -3723,9 +3723,11 @@ static int pci_probe(struct pci_dev *dev version = reg_read(ohci, OHCI1394_Version) & 0x00ff00ff; ohci_notice(ohci, "added OHCI v%x.%x device as card %d, " - "%d IR + %d IT contexts, quirks 0x%x\n", + "%d IR + %d IT contexts, quirks 0x%x%s\n", version >> 16, version & 0xff, ohci->card.index, - ohci->n_ir, ohci->n_it, ohci->quirks); + ohci->n_ir, ohci->n_it, ohci->quirks, + reg_read(ohci, OHCI1394_PhyUpperBound) ? + ", >4 GB phys DMA" : ""); return 0;
-- Stefan Richter -=====-====- ---= =--=- http://arcgraph.de/sr/
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