Recently a customer case came with following - "It appears that the customer has hit the issue in the above [1] CR where the IP Instances introduced in the S10 Update 4 KU is preventing the use of ndd to enable ip debug with ndd as done in the past. The customer feels that having to use mdb to do it on a live, running system is risky and not user friendly. The previous ability to use ndd should be restored/corrected in their opinion."
[1] 6621665 IP Instances removed console printing when ndd -set /dev/ip ip_debug 1 Though I understand facility provided by ip_debug is being planned to be provided by SDT probes, above quote points to the general feeling towards modifying anything on a live system using mdb -kw. And there are reasons for it - I do recall someone mentioned a system crash while attempting to modify a variable using mdb. It was definitely not a bug in mdb, I'd guess it was a typo. mdb -kw is unforgiving to user errors. There had been suggestions to pass a script to customers to modify variables through mdb e.g. # echo "ip_debug/W 0xa"|mdb -kw which will work fine in most of the cases but will fail in certain cases where customer has to use it in both 32 bit and 64 bit kernels. e.g. variables like ip_rput_pullups which are of type long differs in size - 4 bytes on 32 bit kernel vs 8 bytes on 64 bit kernel. It's easy to miss this subtle point when writing a script. Perhaps, Brussels can deliver a mdb dcmds, say, "::assign". This dcmd can check the size of the variable and then writes to it. I'm not sure if it will make customer feel completely comfortable, it certainly will help. - prakash _______________________________________________ networking-discuss mailing list [email protected]
