Hi All, I am developing a HDLC driver for the MPC8358 processor. This HDLC driver will control the UCC(unified communication controller) 8 of the MPC8358 core. The problem I am facing is whenever I submit a packet to the UCC8 HDLC controller to transmit my kernel crashes. It seems there is a memory corruption happening since the crash point varies with each iteration. The following is what I am doing
1) the GUMR register is configured(as per the user manual) 2) The Tx and Rx bd ring memory is allocated from the system memory(using kmalloc). 3) In the HDLC PARAMETER RAM memory map the RBASE and TBASE registers are filled by converting the virtual addresses of the Tx and Rx bds to physical address. 4) The parameter RAM is allocated from the qe memory from offset 0x3600 (as mentioned in ........ 5) There are two 16 bit registers in the parameter RAM memory base named RIPTR and TIPTR( I am not sure if it needs to be filled, it is currently initialized to 0x00000000). a. As per the PPC user manual, a 32 byte memory aligned on a 32 byte boundary should be allocated and its pointer to be stored in these registers but since kmalloc returns a 32 bit pointer how can it be written into a 16 bit register. 6) If I do not set the T_R(transmit ready bit that instructs the HDLC controller to transmit a packet) than my driver is ok(of course its not trying to send the packet and after some time the queue gets full) and the kernel doesn't crashes but if I set the T_R bit and the application tries to send something using my hdlc driver, then the kernel crashes. Any pointers towards finding what could be the possible reason of the crash and how to debug the crash shall be highly appreciated. Regards, Debasish Biswal Phone:+91-124-4340845 Fax: +91-124-4340555 Email: [EMAIL PROTECTED]
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