e1000e and the joy of development kernels [LWN.net]

e1000e and the joy of development kernels

Posted Sep 25, 2008 16:42 UTC (Thu) by aegl (subscriber, #37581)
Parent article: e1000e and the joy of development kernels

Why is it so hard to restore the eeprom (given that it seems to be so easy to overwrite it!).

Most of the data should be the same from one system to another ... so if you can find another system with the same rev of the e1000, you can copy from there). The exception being the MAC address. You can almost certainly find that by searching the /etc/... files that your distro set up for the NIC when it installed the system (on RHEL look for HWADDR in /etc/sysconfig/network-scripts/ifcfg-eth0). Worst case would be that you make up a new one (being sure to not duplicate some other system on your local network ... but a 48-bit number chosen at random is very, very unlikely to match an existing device).

Am I missing something?

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e1000e and the joy of development kernels

Posted Sep 25, 2008 16:46 UTC (Thu) by corbet (editor, #1) [Link]

I don't know why it's so hard, but the word on the list is that Dave Airlie bricked his laptop (the whole machine, not just the adapter) trying. Not fun.

e1000e and the joy of development kernels

Posted Sep 25, 2008 17:21 UTC (Thu) by dw (subscriber, #12017) [Link]

I read somewhere that affected adaptors may not even show up on the PCI bus, which I (in my hardware-uninitiated state) imagine would make it hard to discover where to write the new EEPROM data to.

e1000e and the joy of development kernels

Posted Sep 25, 2008 19:43 UTC (Thu) by iabervon (subscriber, #722) [Link]

I'd guess that the EEPROM contains some information about how the chipset is connected together, to the rest of the machine, and to the ethernet jack, meaning that you have to find an identical device, not just another e1000e, and putting something plausible but wrong could make it do further damage. (In particular, I wouldn't be too surprised if the device checks the eeprom checksum, if that's okay, initializes the PHY, and waits for that before setting up PCI bus interactions; if the checksum is good but the PHY info is wrong, it'll wait forever.)