Linux interrupt management - layers of interrupt management: Hardware: Hardware <-> General Interrupt Controller Process Arch Management: CPU interrupt Interrupt Controller Mangement: IRQ Interrupt # mapping - General Interrupt Controller workflow 1. When GIC detects an interrupt, mark the status of it into pending 2. Distributor Unit will assign the interrupt to target CPU 3. For each CPU…

Common commands # compare changes show | compare # show specific block show | find protocols # save config to file 'common' save common # load config from file 'common' load override/merge common # commit changes commit ? # show options commit check # check correctness of the config commit confirmed # automatically…

Deref & -> get reference of the var * -> deref an address Without the Deref trait, the compiler can only dereference & references. …

Usage of Kprobe KProbes is a debugging mechanism for the Linux kernel which can also be used for monitoring events inside a production system. Fetch layout FETCHARGS : Arguments. Each probe can have up to 128 args. %REG : Fetch register REG @ADDR : Fetch memory at ADDR (ADDR should be in kernel) …

General Setup In this introduction, we use Virtualbox as our VM environment. Here are the three servers we need: LVS server : 2CPU core, 2G Ram, Host network vboxnet 2, vboxnet 3 Service server : 1CPU core, 1G Ram, Host network vboxnet 2, vboxnet 3 Test server: 1CPU core, 1G Ram, Host…

Cisco Router # help ? # enable the privileged exec enable # exit from the privileged exec disable # modify system wide configuration, should enter global configuration mode configure terminal # change interface interface FastEthernet0/0 # enable ip forwarding ip routing # disable ip forwarding no ip routing # enable or disable…

How does OS do the protection mechanism? From Segment Descriptor side When OS loading the segment descriptor to the segment register it will check the type in segment descriptor table CS register can only load the descriptors with Executable flag DS(data segment register) permits the descriptors with Readable flag SS can load the descriptors with Writable flag …

Watch # Incoming Network connection watch ss -tp #-t Turn off the header showing the interval, command #-p Make watch attempt to run command every interval seconds # etc: watch the content of a directory change watch -d ls -l watch -d 'ls -l | fgrep brian' Netstat # Get…

How does a linear address come from? Linear Address = Segment_Base + Effective Address Segment Base is from Segment Descriptor Now we talk about how to generate Segment Base Address The process to get Segment Base Address Segment Selector to find the index in Segment Descriptor idx = segment_selector >> 3 TI (Table Indicator) : A zero indicates the GDT; a one indicates the…