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| -rw-r--r-- | c/src/lib/libbsp/m68k/mvme162/README | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/c/src/lib/libbsp/m68k/mvme162/README b/c/src/lib/libbsp/m68k/mvme162/README index 4f4a263722..af6082db21 100644 --- a/c/src/lib/libbsp/m68k/mvme162/README +++ b/c/src/lib/libbsp/m68k/mvme162/README @@ -28,6 +28,25 @@ any case I am ready to answer questions regarding the port and intend to follow the future RTEMS versions. I will do my best to provide whatever support I can afford time-wise. +MVME162FX and DMA on the IP bus +------------------------------- + +From Eric Vaitl <eric@viasat.com>: + +If you have any customers that will be using the 162FX, tell them to +be careful. The main difference between the 162 and the 162FX is DMA +on the IP bus. I spent over a month trying to write a DMA HDLC driver +for GreenSprings IP-MP and couldn't get it to work. I talked to some +people at GreenSprings, and they agreed that there really is no way to +get DMA to work unless you know the size of the packets in advance. +Once the IP2 chip DMA controller is given the character count and +enabled, it doesn't accept further commands until all of the +characters have arrived. The only way to terminate a DMA transfer +prematurely is by raising DMAEND* during the last read. None of the IP +modules that I know of are currently able to do that. GreenSprings is +working on the problem, but nothing is going to available for a few +months. + Installation ------------ Nothing unique to the MVME162. It has been incorporated into the |