G'day Mikus, The XO-1 SD card slot power supply circuit does not have a discharge clamping function, and so when the firmware or software turns off the power to the slot, the voltage falls slowly.
The fall rate violates the specification for cards. We have seen cards becoming confused because of the slow fall time. When they are confused, we saw I/O errors or failure to respond. Whether the card did this or not varied across cards, across laptops, but mostly based on how long it is unpowered. When an SD card is used as the boot media, it remains powered, and so one would typically not see this symptom. Open Firmware briefly powers the SD card slot during boot, as part of the search for an operating system to boot. If a card is in the slot, then it will experience a brief period of power courtesy of Open Firmware, then a somewhat random interval will elapse before your mount script powers it again. So there is a stochastic or unpredictable response. The gradual churn of functionality on our 12.1.0 builds might easily be moving the goal posts for you. I don't know for sure if this is the cause of what you are experiencing, but you might try a few workarounds, and based on the success of these workarounds you might be able to draw a conclusion. You might work around the problem by: - adding more time before mounting the card, of the order of several seconds, to allow the card to reset, (e.g. a sleep command before your mount command), - detecting the problem, unmounting the card, waiting for a minute, then mounting it again, (e.g. using an alternate console or network access), - using a custom Open Firmware that does not access the SD card slot before boot; http://dev.laptop.org/~quozl/q2f11jb.rom has the boot device search list truncated to only internal storage, this can be checked with ok printenv boot-device There may also be kernel-level things that can be done, but I'm not aware of them. If you were facing the problem with booting from SD card, then I would look into increasing the power-off-time in a new build of Open Firmware. It is currently 250ms on XO-1: ok dev /pci/sd power-off-time .d 250 -- James Cameron http://quozl.linux.org.au/ _______________________________________________ Devel mailing list [email protected] http://lists.laptop.org/listinfo/devel
