Ground Zero: Computer Hardware, Kernel Space, User Space & Syscalls

Lab 01 of 20 · Ground Zero Basics · 5 hands-on activities · bilingual (English + සිංහල)

පිටුව 01: පරිගණක මූලිකාංග, Linux Kernel එක, User Space සහ Syscalls

Hardware (CPU, RAM, Disk), Linux Kernel එකේ කාර්යභාරය, CPU Protection Rings (Ring 0 vs Ring 3), සහ System Calls (Syscalls) ක්‍රියාත්මක වන ආකාරය සරලව ඉගෙන ගනිමු.

Architectural Foundation & Systems Diagram

Every journey in Site Reliability Engineering and DevOps begins at the hardware and operating system layer. Before containers or clouds exist, code runs on physical silicon managed by the Linux kernel.

• 🖥️ CPU, RAM & Disk — The CPU calculates instructions at gigahertz speed. RAM provides ultra-fast temporary working memory. Disk provides permanent persistent storage. The OS coordinates all three.

• 🛡️ Why Ring 0 vs Ring 3? — Hardware protection rings ensure that if a user application (like a web browser or Python script) crashes or has a memory leak, it cannot corrupt physical memory or crash the entire machine.

• 🚪 System Calls (Syscalls) — Whenever a program wants to read a file from disk, allocate memory, or send a network packet over the Internet, it MUST make a system call asking the Linux kernel to perform the action safely on its behalf.

Step-by-step practical lab

Step 01: Verify Local Loopback Network Interface

සිංහලෙන් — පරිගණකයේ internal networking stack එක නිවැරදිව ක්‍රියාත්මක වේදැයි පරීක්ෂා කිරීම.

Send 4 ICMP network echo requests to localhost (127.0.0.1) to confirm your network protocol stack is initialized.

ping -c 4 localhost

• -c 4 : Count: Packets 4ක් පමණක් යවා ස්වයංක්‍රීයව නවත්වයි.

Expected output

PING localhost (127.0.0.1) 56(84) bytes of data.
64 bytes from localhost: icmp_seq=1 ttl=64 time=0.038 ms
4 packets transmitted, 4 received, 0% packet loss

Step 02: Probe HTTP Web Response Headers via Curl

සිංහලෙන් — Web Server එකක් වෙත HTTP GET request එකක් යවා එහි Headers කියවීම.

Fetch only the HTTP response status code and headers from port 8080 without downloading the HTML payload body.

curl -I http://localhost:8080

• -I : Headers පමණක් ලබාගැනීම: Server එකේ වර්ගය සහ HTTP 200 OK තත්ත්වය පරීක්ෂා කරයි.

Expected output

HTTP/1.1 200 OK
Server: nginx/1.24.0 (Ubuntu)
Date: Wed, 16 Sep 2026 12:50:00 GMT
Content-Type: text/html

Step 03: Inspect Machine Network Hostname

සිංහලෙන් — Server එකේ ජාල නාමය (Hostname) පරීක්ෂා කර තහවුරු කර ගැනීම.

Query the assigned network hostname of the current operating system instance.

hostname

• hostname : /etc/hostname ගොනුවේ ඇති server එකේ නම පෙන්වයි.

Expected output

prod-app-srv-01.internal.cloud

Hands-on practice activities

Work through these yourself — tick them off as you go.

• Activity 01: Inspect Linux Monolithic Kernel Architecture (Drill) — Query the running monolithic Linux kernel version, machine hardware name, and kernel build architecture (x86_64).
• Activity 02: Read Kernel Release Metadata (Drill) — Inspect the GCC compiler version and Linux kernel build timestamp directly from the /proc virtual filesystem.
• Activity 03: Test Local Network Loopback Stack (Drill) — Send 4 ICMP echo request packets to 127.0.0.1 to verify your kernel TCP/IP network stack is initialized.
• Activity 04: Inspect Host Machine Name (Drill) — Query the assigned network hostname of the current operating system instance.
• Activity 05: CPU Rings & Privilege Level Check (Quiz) — In which CPU protection ring does the Linux kernel run with unrestricted hardware access? Answer: Ring 0.

Keep going: ← Series overview · Lab 02 → · Track your progress in the Self Guide