HOTPLUG

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