diff options
Diffstat (limited to 'Documentation/debugging-via-ohci1394.txt')
| -rw-r--r-- | Documentation/debugging-via-ohci1394.txt | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/Documentation/debugging-via-ohci1394.txt b/Documentation/debugging-via-ohci1394.txt index 73473aa8d861..fa0151a712f9 100644 --- a/Documentation/debugging-via-ohci1394.txt +++ b/Documentation/debugging-via-ohci1394.txt @@ -22,10 +22,12 @@ locations such as buffers like the printk buffer or the process table. Retrieving a full system memory dump is also possible over the FireWire, using data transfer rates in the order of 10MB/s or more. -Memory access is currently limited to the low 4G of physical address -space which can be a problem on IA64 machines where memory is located -mostly above that limit, but it is rarely a problem on more common -hardware such as hardware based on x86, x86-64 and PowerPC. +With most FireWire controllers, memory access is limited to the low 4 GB +of physical address space. This can be a problem on IA64 machines where +memory is located mostly above that limit, but it is rarely a problem on +more common hardware such as x86, x86-64 and PowerPC. However, at least +Agere/LSI FW643e and FW643e2 controllers are known to support access to +physical addresses above 4 GB. Together with a early initialization of the OHCI-1394 controller for debugging, this facility proved most useful for examining long debugs logs in the printk @@ -99,6 +101,9 @@ Step-by-step instructions for using firescope with early OHCI initialization: compliant, they are based on TI PCILynx chips and require drivers for Win- dows operating systems. + The mentioned kernel log message contains ">4 GB phys DMA" in case of + OHCI-1394 controllers which support accesses above this limit. + 2) Establish a working FireWire cable connection: Any FireWire cable, as long at it provides electrically and mechanically |