[c-nsp] strange npe-225 and 7206 non-vxr crashes

[Ed Ravin]

I just purchased an NPE-225 with 256 MB memory from someone on Ebay.
I yanked the NPE-200 from my existing 7206 router (non-VXR), and fired
it up with the new board.  The first message after the bootstrap was
rather inausipicious:

   Bad CPU ID 000028A0

But the router kept going, and worked for five minutes.  Then it died
with this error:

   Error: (rsvd) instr cache, fields: data, SysAD
   virtual addr 0x60109CE6, physical addr(21:3) 0x109CE0, vAddr(14:12) 0x1000
   virtual address corresponds to main:text, cache word 0

                Low Data   High Data  Par    Low Data   High Data  Par
   L1 Data  : 0:0x10A00003 0x00000000 0x03 1:0x0C041217 0x0240202D 0x03
              2:0x32050021 0x10A00003 0x03 3:0x00000000 0x0C041E39 0x01

    Invalid CPU type 28

    Interrupt exception, CPU signal 20, PC = 0x60109CE0

I researched the "Bad CPU ID" message, and upgraded the bootflash.  Now,
I get something else upon powerup, just after the bootflash is loaded:

   *** Emulating mis-aligned load at 0x87ff1adf
       PC = 0x87ff7820 ... succeeded

   *** Trap Exception ***
   PC = 0x87ff7824, Cause = 0x34, Status Reg = 0x3040d003

   monitor: command "boot" aborted due to exception

The router then reloads the bootstrap, reloads the bootflash, and successfully
boots into IOS.  But then the router crashes again, with this info in the
crashinfo file:

 Error: (rsvd) instr cache, fields: data, SysAD
 virtual addr 0x60104881, physical addr(21:3) 0x104880, vAddr(14:12) 0x0000
 virtual address corresponds to main:text, cache word 0

              Low Data   High Data  Par    Low Data   High Data  Par
 L1 Data  : 0:0xAFB10044 0xAFB00040 0x02 1:0xAFA40068 0x8C9E0194 0x03
            2:0x8FC20068 0x8FC30060 0x01 3:0x8FD20078 0x00021100 0x00

              Low Data   High Data  Par    Low Data   High Data  Par
 DRAM Data: 0:0xAFB10044 0xAFB00040 0x02 1:0xAFA40068 0x8C9E0194 0x03
            2:0x8FC20068 0x8FC30060 0x01 3:0x8FD20078 0x00021100 0x00

  Interrupt exception, CPU signal 20, PC = 0x60104880


So what might be going on here?  If it's a hardware error, why does
it even boot all the way up on the second try?  I see that updating
the bootflash got rid of the "Invalid CPU Type" error in the crashinfo,
but there's clearly something else going on...