Binutils LD creates huge files - ld

Question

I'm trying to create as small ELF as possible. I created a test file like this (NASM syntax):
SECTION .text
dd 0xdeadbeef
With this linker script:
SECTIONS {
.text : {
*(.text)
}
}
Then I checked sizes of flat binary and ELFs built two ways:
nasm -f bin -o test test.asm
It's flat binary, so 4 bytes.
nasm -f elf -o test.o test.asm
i686-elf-ld -Tlinker.ld test.o -o test
I'd expect something like 500 bytes max, but the resulting file is 4396 bytes long! There is an option however, named --strip-all, that could make this file smaller.
i686-elf-ld -Tlinker.ld test.o -o test --strip-all
4244 bytes. Still huge.
Why is LD generating so big files? Is there a way to make it smaller?

Answer 1

The linker is page aligning your text section to the nearest page boundary so that demand paging can be used.
$ objdump --headers -f test
test: file format elf32-i386
architecture: i386, flags 0x00000102:
EXEC_P, D_PAGED
start address 0x00000000
Sections:
Idx Name Size VMA LMA File off Algn
0 .text 00000004 00000000 00000000 00001000 2**4
CONTENTS, ALLOC, LOAD, READONLY, CODE
Notice the "Align" column of the text section is set to 4KB. Because of the alignment is set to 4Kb and demand paging is in use (D_PAGED), the .text section is located 4Kb into the file. Your text section is only 4 bytes long.
Link with -n to disable demand paging:
$ ld -Tlinker.ld test.o -o test --strip-all -n
$ objdump --headers -f test
test: file format elf32-i386
architecture: i386, flags 0x00000002:
EXEC_P
start address 0x00000000
Sections:
Idx Name Size VMA LMA File off Algn
0 .text 00000004 00000000 00000000 00000060 2**4
CONTENTS, ALLOC, LOAD, READONLY, CODE
$ ls -l test
-rwxrwxr-x 1 mikel mikel 240 Apr 15 12:31 test