Question about my linker script
Posted: Fri May 13, 2016 2:54 pm
I was following a tutorial, and copied the linker script they gave me. Down the road, I needed to figure out the memory location of my kernel (as well as the end) so I can remove it from the available memory given to me by GRUB.
The internet suggested adding the lines kernelStart = .; and kernelEnd = .; at the appropriate positions and access them via extern variables from C. I did this and I am not sure where to put kernelEnd.
Could somebody please explain what all the different sections are as well as the best place for kernelEnd?
The internet suggested adding the lines kernelStart = .; and kernelEnd = .; at the appropriate positions and access them via extern variables from C. I did this and I am not sure where to put kernelEnd.
Could somebody please explain what all the different sections are as well as the best place for kernelEnd?
Code: Select all
/* The bootloader will look at this image and start execution at the symbol
designated as the entry point. */
ENTRY(_start)
/* Tell where the various sections of the object files will be put in the final
kernel image. */
SECTIONS
{
/* Begin putting sections at 1 MiB, a conventional place for kernels to be
loaded at by the bootloader. */
. = 1M;
kernelStart = .;
/* First put the multiboot header, as it is required to be put very early
early in the image or the bootloader won't recognize the file format.
Next we'll put the .text section. */
.text BLOCK(4K) : ALIGN(4K)
{
*(.multiboot)
*(.text)
}
kernelEnd = .; // my code works with this here, but I'm not sure if it's the best spot
/* Read-only data. */
.rodata BLOCK(4K) : ALIGN(4K)
{
*(.rodata)
}
/* Read-write data (initialized) */
.data BLOCK(4K) : ALIGN(4K)
{
*(.data)
}
/* Read-write data (uninitialized) and stack */
.bss BLOCK(4K) : ALIGN(4K)
{
*(COMMON)
*(.bss)
*(.bootstrap_stack)
}
/* The compiler may produce other sections, by default it will put them in
a segment with the same name. Simply add stuff here as needed. */
}