Hiring guide for GAS (GNU Assembler) Engineers

GAS (GNU Assembler) Developer Hiring Guide

The GNU Assembler, also known as GAS, is a free and open-source assembler for the x86 architecture. It was originally developed by Richard Stallman and released in 1987 as part of the GNU Compiler Collection (GCC). GAS is now maintained by the Free Software Foundation and is included in most Linux distributions. GAS is a powerful and versatile assembler that can be used to create both simple and complex programs. It supports a wide range of features, including macros, conditional assembly, and inline assembly. GAS is also highly portable and can be used on a variety of platforms. Sources: [1] https://en.wikipedia.org/wiki/GNU_Assembler [2] https://gcc.gnu.org/onlinedocs/gcc/GAS-Intro.html

Ask the right questions secure the right GAS (GNU Assembler) talent among an increasingly shrinking pool of talent.

First 20 minutes

General GAS (GNU Assembler) app knowledge and experience

The first 20 minutes of the interview should seek to understand the candidate's general background in GAS (GNU Assembler) application development, including their experience with various programming languages, databases, and their approach to designing scalable and maintainable systems.

What is the purpose of a linker in GAS?
A linker in GAS is used to combine multiple object files into a single executable. It resolves symbols and addresses, allowing for separate compilation of source files.
How would you declare a global variable in GAS?
A global variable in GAS can be declared using the .globl directive. For example: .globl myVariable
What is the role of the .data directive in GAS?
The .data directive is used to declare initialized data or variables. It tells the assembler to place the data in the data segment of the object file.
How would you perform a bitwise operation in GAS?
Bitwise operations in GAS can be performed using the AND, OR, XOR, and NOT instructions. For example, to perform a bitwise AND operation, you can use the AND instruction like this: AND %eax, %ebx.
What are the different sections of a GAS source file?
A GAS source file typically contains three sections: .data for initialized data, .bss for uninitialized data, and .text for the code.
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What you’re looking for early on

Does the candidate show a strong understanding of GAS syntax and architecture?
Has the candidate demonstrated the ability to write efficient and optimized assembly code?
Can the candidate effectively debug and troubleshoot assembly code?
Does the candidate have experience with version control systems like Git?

Next 20 minutes

Specific GAS (GNU Assembler) development questions

The next 20 minutes of the interview should focus on the candidate's expertise with specific backend frameworks, their understanding of RESTful APIs, and their experience in handling data storage and retrieval efficiently.

How would you use the .equ directive in GAS?
The .equ directive in GAS is used to give names to constants. For example: .equ PI, 3.14159. This assigns the value 3.14159 to the symbol PI.
Describe the difference between the .bss and .data sections in GAS.
The .bss section is used for declaring variables that are not initialized, while the .data section is used for declaring initialized data or variables.
How would you write a loop in GAS?
Loops in GAS can be written using jump instructions and labels. For example, a simple loop can be written as follows: loop: instructions jmp loop
What are the uses of the push and pop instructions in GAS?
The push and pop instructions are used for stack operations. The push instruction pushes a value onto the stack, while the pop instruction removes the topmost value from the stack.
Describe the difference between the move and lea instructions in GAS.
The move instruction is used to copy a value from one location to another, while the lea instruction is used to load the address of a memory location into a register.
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The ideal back-end app developer

What you’re looking to see on the GAS (GNU Assembler) engineer at this point.

At this point, a skilled GAS (GNU Assembler) engineer should demonstrate strong problem-solving abilities, proficiency in GAS (GNU Assembler) programming language, and knowledge of software development methodologies. Red flags include lack of hands-on experience, inability to articulate complex concepts, or unfamiliarity with standard coding practices.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with GAS (GNU Assembler).

What does this simple GAS assembly code do?
.globl _main
	movl $42, %eax
This code sets the value 42 in the EAX register and then returns from the main function. It's equivalent to a C program that has a main function which returns 42.
What does this GAS syntax do?
movl $0, %eax
movl $0, %ebx
idivl %ebx
This code attempts to divide the value in the EAX register by the value in the EBX register. However, as the value in EBX is 0, this will cause a divide by zero exception.
What does this GAS code do with an array?
.section .data
	.long 1, 2, 3, 4, 5
.section .text
.globl _main
	movl array(,%eax,4), %eax
This code defines an array with five elements in the data section. In the main function, it uses the EAX register as an index to access an element from the array, multiplies it by 4 (the size of a long integer), and then stores the result back in the EAX register.
What does this GAS code do with threads?
.section .data
value: .long 0
.section .text
.globl _main
	lock addl $1, value
This code defines a long integer variable named 'value' in the data section and initializes it with 0. In the main function, it uses the 'lock' prefix to perform an atomic addition operation, adding 1 to the value. This ensures that the operation is thread-safe.

Wrap-up questions

Final candidate for GAS (GNU Assembler) Developer role questions

The final few questions should evaluate the candidate's teamwork, communication, and problem-solving skills. Additionally, assess their knowledge of microservices architecture, serverless computing, and how they handle GAS (GNU Assembler) application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

How would you handle errors in GAS?
Errors in GAS can be handled using the .err and .error directives. The .err directive generates an error if the preceding instruction is assembled, while the .error directive generates an error with a specified message.
What are the different types of operands in GAS?
GAS supports several types of operands including immediate values, registers, memory references, and labels.
How would you implement a subroutine in GAS?
A subroutine in GAS can be implemented using the call and ret instructions. The call instruction jumps to a subroutine, and the ret instruction returns from a subroutine.

GAS (GNU Assembler) application related

Product Perfect's GAS (GNU Assembler) development capabilities

Beyond hiring for your GAS (GNU Assembler) engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in GAS (GNU Assembler) projects, and can engage in multiple capacities.