Excuse me in advance if this is too long. Let me explain what I'm trying to do: I'm using the uengine interrupt to StrongARM to ask for an ARP service performed by VxWorks. I'm not using the OS ARP Cache directly from uengines, rather I maintain a private hash table (SRAM and DRAM) for IP to MAC entries. This table is written by the core and read by uengines. All locking, hash unit and duplicates issues are just fine. When a lookup from uengine thread fails to find an entry for IP (the MAC is unknown!), the uengine thread will write the request in a mailbox and raise an interrupt to core. ACK from core is waited (inter thread signal). when ACK received, uthread will drop the packet, hopefully next packet required MAC will be resolved since ARP Service on core will add the information to IP2MAC table. On core there is an interrupt handler, that is a callback function registered with the Global uengine ISR (yeah, the same one breakpoint is using!). This handler will read the uthread request from mailbox and send it by message queue to ARP resolver task. The interrupt handler send an inter thread signal as an ACK back to uengines. The ARP resolver task perform the ARP and adds the resolved MAC to IP2MAC hash table. some code snippets: #macro arp_resolve_request(_output_intf, _ip) .local mailbox xbuf_alloc($request, 2) move($request0, _output_intf) move($request1, _ip) #if (UENGINE_ID == 0) move(mailbox, LWOFFSET0) #else // UENGINE_ID == 1 move(mailbox, LWOFFSET2) #endif sram_write($request0, UTHREAD_TO_CORE_MAILBOXES, mailbox, LWCOUNT2, sig_done) block_on_sram#: br_!signal[sram, block_on_sram#] ; block until mailbox written to continue fast_wr[1, ireg] ; raise interrupt block_on_inter_thread#: br_!signal[inter_thread, block_on_inter_thread#] ; wait for core ACK xbuf_free($request) alu[--,--,b, 0] ; this will cause drop pkt .endlocal // mailbox #endm note that I use only the first 2 (0, 1) uengines to Receive & Forward so just two mailboxes. now at the core... I connect the interrupt handler as: #include "ueng.h" ......... /* statics initialization */ unsigned int & ArpServ::_ireg(*(unsigned int *)0xB00401E0); ................. uEng_intConnect(UENG_MSG_INT, 0xFFFFFF, interrupt_handler, 0); ................ void ArpServ::interrupt_handler(int){ REQUEST_t request; unsigned int ifname, ipaddr, request_size; unsigned int iregShadow; iregShadow= _ireg; _ireg = iregShadow & 0xF8FFFFFF; iregShadow &= 0xFFFFFF; for(int bit=0; bit> 2) ? REQ_SIZE : 0; READ_MAILBOX(request_size, ifname, ipaddr); request.ifname = ifname; request.ipaddr = ipaddr; logMsg("request.ifname = %d request.ipaddr = 0x%08x\n", request.ifname, request.ipaddr, 3, 4, 5, 6); msgQSend(msgQId, (char *)&request, REQ_SIZE, 0, 0); /* ack uengine thread by inter thread signal */ *(unsigned int *)0xB00401C0 = bit; } } } At this point let me thank you for reading so far! Now the problem: 3 boards with same configuration work inconsistently. Board A always performs as expected. Board B and Board C not always. The interrupt isn't received on core. BUT, when I set breakpoint in uthread and stop as close before the fast_wr instruction (on sram_write) then just continue running interrupt is received on core! Then even if I unset the breakpoint the board function as expected The software looks OK and (surprisingly :-) it sometimes (always on one of the Boards) work as expected. Is it some timing issue with SRAM reference? Maybe I mask something wrong in ireg and not register proper to ISR? At the time of writing this an idea came to me: I should link out debug from vxworksnetapp so Breakpoint interrupt handler is not getting connected. Could this be a H/W problem?! Any ideas and all are welcomed ! Arthur Berkowitz COMGATES Ltd. 15 Hagalim Avenue. Herzliya, 46725 Israel Tel: +972.9.950.0404 Ext: 288 Fax: +972.9.950.0385 Mobile: +972.55.535.349 Email: arthur@comgates.co.il Visit Us: www.comgates.com