The relationship between devmgr and devhost Let's move on to see what devmgr threads do today.After the latest version of Agata runs on Qemu, the following hierarchy appears after running the command "ps-T":
$ ps -T
TASK PSS PRIVATE SHARED STATE NAME
j:1028 38.5M 37.0M root
p:1043 9894.0k 9892k 28k bin/devmgr
t:1046 blocked bin/devmgr
t:1084 blocked mxio-dispatcher
t:1100 blocked local-multiloader
t:1135 blocked service-starter
j:1075 26.4M 25.7M magenta-drivers
p:1168 430.0k 428k 28k /boot/bin/acpisvc
t:1218 blocked initial-thread
t:1370 blocked thrd_t:0x36b0ee2cfb30/TLS=0x4f8
t:1378 blocked thrd_t:0x36f9fdcb2b30/TLS=0x4f8
p:1539 202.0k 200k 28k devhost:root
t:1563 blocked initial-thread
p:1576 566.0k 564k 28k devhost:misc
t:1599 blocked initial-thread
t:1879 blocked debug-reader
t:1990 blocked i8042-kbd-irq
t:2107 blocked dmctl-multiloader
t:2290 blocked i8042-mouse-irq
p:1719 994.0k 224k 1564k devhost:pci#1:1234:1111
t:1742 blocked initial-thread
p:1781 24.3M 24.3M 28k devhost:pci#3:8086:2922
t:1823 blocked initial-thread
t:1945 blocked ahci-irq
t:1950 blocked ahci-watchdog
t:1955 blocked ahci-worker
j:1087 2456.0k 1672k magenta-services
p:1089 254.0k 252k 28k crashlogger
t:1122 blocked initial-thread
t:1363 blocked self-dump-thread
p:1157 1078.0k 308k 1564k virtual-console
t:1193 blocked initial-thread
p:1198 166.0k 164k 28k netsvc
t:1237 blocked initial-thread
p:2000 226.0k 224k 28k sh:console
t:2052 blocked initial-thread
p:2095 186.0k 184k 28k vc:sh
t:2130 blocked initial-thread
p:2167 186.0k 184k 28k vc:sh
t:2192 blocked initial-thread
p:2229 190.0k 188k 28k vc:sh
t:2254 blocked initial-thread
p:2424 170.0k 168k 28k /boot/bin/ps
t:2457 running initial-thread
j:1088 0B 0B fuchsia
TASK PSS PRIVATE SHARED STATE NAME
Where "j" means Job, "p" means Process, "t" means Thread.The process bin/devmgr has four threads with the following roles:
bin/devmgr
This is the main thread, which listens for device events and handles them as a daemon thread after initialization.Mainly handles add, remove, bind requests for device initiated by devhost.
In implementation, we listen on a specific port object, dc_port, and the fallback handler is dc_handle_device.Dc_port listens for devhost's request channel, and when a new device is created based on devhost's request, it listens for device's request channel in response to deice's operation request.The object type of the callback is port_handler_t.
mxio-dispatcher
It also uses listening port s and handling related events.For access to the main processing files, see mxrio_handler and vfs_handler.Its file operation requests come from various processes.
local-multiloader
When launchpad runs an application or service, you need to request the loader service to load the file.Initialization of this service is shown in mxio_loader_service.It creates a thread called "local-multiloader", which listens for port, and the event fallback function is multiloader_cb, which calls default_load_object to load the file.
service-starter
The entry function for this thread is service_starter, which, after starting some services, listens on the folder "/dev/class/block" as a daemon thread. If a new file appears in this folder, a new block device is added.Call back function block_device_added to process this device.Usually mount this device.