The FIFO in the CPM for the FCCs is 192 bytes. If you can send short packets but not longer packets, it implies that the CPM is OK as long as the whole packet will fit into the FIFO. As soon as it has to start flushing to memory, things fall apart. My experience is that it starts falling apart around 200-250 bytes -- the FIFO can flush a few bytes out, but then falls behind and things stop.
You probably have a memory or clocking issue. How fast are you clocking your CPM and how fast is your ethernet? If you are running 100bT, you need to clock your CPM at 100MHz or better. Also, don't clock it with a 2.5x multiplier: that invokes a REALLY BAD silicon bug in the A.1 processor (others?). There are even more issues with silicon prior to A.1 and you should upgrade if you are running old silicon. Device errata (file name XPC8260A.IDE.pdf) ------------------------------------------------------------------------ XPC8260 DEVICE ERRATA December 18, 2000 This document is a compilation of device errata for Revision A.1. Herein, the errata are classified and numbered, and most erratum is provided with a description and workarounds. This is a pre-production device errata. New addition/change to the errata since the last revision is indicated with ITALIC font. [snip] CPM62. THE CPM PLL DOES NOT LOCK RELIABLY FOR CERTAIN MULTIPLICATION FACTORS. If the CPM multiplication factor is 2.5, 3.5, 5 or 6 the internal PLL will not lock reliably which will result in erratic behavior. Sometimes (mainly at bus frequencies lower than 50 Mhz) it might lock, however it might loose the lock after worth. If one of the other multiplication factors (2,3 or 4) is selected, the CPM PLL will lock reliably, even at 66 Mhz bus speed. Workaround: Do not use the non-reliable multiplication factors. For 166 Mhz CPM use 55 Mhz bus frequency and a CPM multiplication factor of 3. Fix plan: TBD ------------------------------------------------------------------------ Mask info: Rev Mask Process Qual IMMR[16:31] 0.2 2J24M 0.29 um HIP3 - 0x0000 A.0 K22A 0.29 um HIP3 - 0x0010 A.1 1K22A 0.29 um HIP3 XC 0x0010 Note: My A.1 processors IMMR read 0x0011, I presume the table entry is a typo. gvb At 10:40 AM 4/5/01 +0800, machael wrote: >Hello, > > Now I can run linuxppc-2.4.3-pre4 (from ftp.denx.de) on my >8260-based custom board sucessfully . > I met a strange problem when ping this target board. When > pinging the >board from my host using "ping -f MyBoardIP " , it works normally. >But if >I ping using "ping -s 200 MyBoardIP", then I can receive no >respondence but >"TIMEOUT". Why? > Do you have such similar problems? What may be the problem? > > Thank you very much! > > machael > > ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/