1. Linux의 HOTPLUG
Hot swap
Hot plug
Cold plug
http://free-electrons.com/doc/udev.pdf
http://blackfin.uclinux.org/doku.php?id=linux-kernel:hotplug
/sbin/mdev
http://git.busybox.net/busybox/plain/docs/mdev.txt
I see the same behaviour with the watchdog device and softdog module
mdev used for hotplugging, echo /sbin/mdev > /proc/sys/kernel/hotplug
/sys/devices/virtual/misc/watchdog
insmod softdog:
/dev/watchdog is added because of hotplugging by mdev, as block device:
brw-rw---- 1 root root 10,130
rm /dev/watchdog, mdev -s:
/dev/watchdog is added as character device:
crw-rw---- 1 root root 10,130
Obviously /usr/sbin/watchdog fails to start in the hotplugging case.
http://creaplz.tistory.com/category/Embedded%20System
http://en.wikipedia.org/wiki/Udev
/proc/sys/kernel/hotplug
http://egloos.zum.com/furmuwon/v/11024586
http://lxr.free-electrons.com/source/lib/kobject_uevent.c?v=3.9
https://wiki.kldp.org/wiki.php/LinuxHotplug
http://git.busybox.net/busybox/plain/docs/mdev.txt
http://lists.busybox.net/pipermail/busybox-cvs/2008-February/026640.html
http://blog.secmem.org/88
http://debian-handbook.info/browse/stable/sect.hotplug.html
/sbin/hotplug
http://www.bangmoney.org/presentations/hotplug/
http://wiki.openwrt.org/doc/techref/hotplug
****
http://forum.falinux.com/zbxe/index.php?document_srl=551671&mid=lecture_tip
CONFIG_HOTPLUG=y
CONFIG_UEVENT_HELPER_PATH=""
CONFIG_NET=y
CONFIG_UNIX=y
CONFIG_SYSFS=y
CONFIG_SYSFS_DEPRECATED*=n
CONFIG_PROC_FS=y
CONFIG_TMPFS=y
CONFIG_INOTIFY_USER=y
CONFIG_SIGNALFD=y
CONFIG_TMPFS_POSIX_ACL=y (user ACLs for device nodes)
CONFIG_BLK_DEV_BSG=y (SCSI devices)
http://hoonycream.tistory.com/entry/udev
http://debian-handbook.info/browse/stable/sect.hotplug.html
http://www.hpl.hp.com/personal/Jean_Tourrilhes/Linux/HOTPLUG-UDEV.txt
ttySAC0 ~ 3은 console device
http://egloos.zum.com/codenakseo/v/4582439
처음 접할때, 확인사항 KERNEL 의 현재 ARCHTYPE,
vi ./include/generated/mach-types.h
MACH_TYPE_
#ifdef CONFIG_ARCH_IXDP425
# ifdef machine_arch_type
# undef machine_arch_type
# define machine_arch_type __machine_arch_type
# else
# define machine_arch_type MACH_TYPE_IXDP425
# endif
# define machine_is_ixdp425() (machine_arch_type == MACH_TYPE_IXDP425)
#else
# define machine_is_ixdp425() (0)
#endif