To Whom It May Concern:
I am observing seL4+VM+ARM behavior on the TK1-SOM that I find very puzzling. Consider the following code:
#define idx(i) (i%16) for(i = 0; i < buf->capacity() && buf->capacity() > 16; i++, pArray++){ mem[idx(i)] = *pArray; }
where 'pArray' is the array representation of 'buf' and 'mem' is a memory mapped page set that corresponds to a page set of memory that is managed by a fault handler in the VMM (something I have installed myself using a 'DEV_CUSTOM' device). This code runs as I would expect. However, the follow code results in an assertion failure in the VMM:
#define idx(i) (i%16) for(i = 0; i < 16; i++, pArray++){ mem[idx(i)] = *pArray; }
The error report follows:
32 bit ARM insts not decoded -------- Pagefault from [Linux]: write fault @ PC: 0xbd7499a8 IPA: 0xe0001000, FSR: 0x2000046 Context: r0: 0xb6d2a050 r1: 0x0 r2: 0xb6ac76b8 r3: 0x4c r4: 0xb6d2a050 r5: 0xb6d2a8ec r6: 0x1 r7: 0xb6d2a050 r8: 0x7fb73000 r9: 0xad13cfff r10: 0xabe31310 r11: 0x19 r12: 0xb6d285d8 pc: 0x7f68f9a8 r14: 0x7f68f99c sp: 0xaf1c3c20 cpsr: 0x80000010 -------- Assertion failed: rt >= 0 (../projects/seL4_projects_libs/libsel4arm-vmm/src/fault.c: get_rt: 357)
Some added information that may be helpful; if the strange modulo operation I am performing on the index is removed I receive a similar crash for both code snippets.
Any thoughts on where I might look to get to the bottom of this problem would be helpful.
Thanks! Dan DaCosta