Based on riscv GNU toolchain.
I suggest you to use the default link script, and add your memory & stack & heap defination.
But remember, add a ".other: { (.) }", in case of there's some of the sections are not defined in the default script.
This is an example:
/* Copyright (C) 2014-2025 Free Software Foundation, Inc.
Copying and distribution of this script, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved. */
OUTPUT_FORMAT("elf32-littleriscv", "elf32-littleriscv", "elf32-littleriscv")
OUTPUT_ARCH(riscv)
ENTRY(_vectors)
SEARCH_DIR("/mnt/riscv/riscv32-unknown-elf/lib");
MEMORY
{
RAM (rwx) : ORIGIN = 0x00000000, LENGTH = 512M
}
SECTIONS
{
/* Custom Entry */
.vectors : {
. = ALIGN(4);
KEEP(*(.vectors))
}
/* Read-only sections, merged into text segment: */
PROVIDE (__executable_start = SEGMENT_START("text-segment", 0x10000));
. = SEGMENT_START("text-segment", 0x10000) + SIZEOF_HEADERS;
/* Place the build-id as close to the ELF headers as possible. This
maximises the chance the build-id will be present in core files,
which GDB can then use to locate the associated debuginfo file. */
.note.gnu.build-id : { *(.note.gnu.build-id) }
.interp : { *(.interp) }
.hash : { *(.hash) }
.gnu.hash : { *(.gnu.hash) }
.dynsym : { *(.dynsym) }
.dynstr : { *(.dynstr) }
.gnu.version : { *(.gnu.version) }
.gnu.version_d : { *(.gnu.version_d) }
.gnu.version_r : { *(.gnu.version_r) }
.rela.dyn :
{
*(.rela.init)
*(.rela.text .rela.text.* .rela.gnu.linkonce.t.*)
*(.rela.fini)
*(.rela.rodata .rela.rodata.* .rela.gnu.linkonce.r.*)
*(.rela.data .rela.data.* .rela.gnu.linkonce.d.*)
*(.rela.tdata .rela.tdata.* .rela.gnu.linkonce.td.*)
*(.rela.tbss .rela.tbss.* .rela.gnu.linkonce.tb.*)
*(.rela.ctors)
*(.rela.dtors)
*(.rela.got)
*(.rela.sdata .rela.sdata.* .rela.gnu.linkonce.s.*)
*(.rela.sbss .rela.sbss.* .rela.gnu.linkonce.sb.*)
*(.rela.sdata2 .rela.sdata2.* .rela.gnu.linkonce.s2.*)
*(.rela.sbss2 .rela.sbss2.* .rela.gnu.linkonce.sb2.*)
*(.rela.bss .rela.bss.* .rela.gnu.linkonce.b.*)
*(.rela.ifunc)
}
.rela.plt :
{
*(.rela.plt)
PROVIDE_HIDDEN (__rela_iplt_start = .);
*(.rela.iplt)
PROVIDE_HIDDEN (__rela_iplt_end = .);
}
/* Start of the executable code region. */
.init :
{
KEEP (*(SORT_NONE(.init)))
}
.plt : { *(.plt) *(.iplt) }
.text :
{
*(.text.unlikely .text.*_unlikely .text.unlikely.*)
*(.text.exit .text.exit.*)
*(.text.startup .text.startup.*)
*(.text.hot .text.hot.*)
*(SORT(.text.sorted.*))
*(.text .stub .text.* .gnu.linkonce.t.*)
/* .gnu.warning sections are handled specially by elf.em. */
*(.gnu.warning)
}
.fini :
{
KEEP (*(SORT_NONE(.fini)))
}
PROVIDE (__etext = .);
PROVIDE (_etext = .);
PROVIDE (etext = .);
/* Start of the Read Only Data region. */
.rodata : { *(.rodata .rodata.* .gnu.linkonce.r.*) }
.rodata1 : { *(.rodata1) }
.sdata2 :
{
*(.sdata2 .sdata2.* .gnu.linkonce.s2.*)
}
.sbss2 : { *(.sbss2 .sbss2.* .gnu.linkonce.sb2.*) }
.eh_frame_hdr : { *(.eh_frame_hdr) *(.eh_frame_entry .eh_frame_entry.*) }
.eh_frame : ONLY_IF_RO { KEEP (*(.eh_frame)) *(.eh_frame.*) }
.sframe : ONLY_IF_RO { *(.sframe) *(.sframe.*) }
.gcc_except_table : ONLY_IF_RO { *(.gcc_except_table .gcc_except_table.*) }
.gnu_extab : ONLY_IF_RO { *(.gnu_extab*) }
/* These sections are generated by the Sun/Oracle C++ compiler. */
.exception_ranges : ONLY_IF_RO { *(.exception_ranges*) }
/* Various note sections. Placed here so that they are always included
in the read-only segment and not treated as orphan sections. The
current orphan handling algorithm does place note sections after R/O
data, but this is not guaranteed to always be the case. */
.note.build-id : { *(.note.build-id) }
.note.GNU-stack : { *(.note.GNU-stack) }
.note.gnu-property : { *(.note.gnu-property) }
.note.ABI-tag : { *(.note.ABI-tag) }
.note.package : { *(.note.package) }
.note.dlopen : { *(.note.dlopen) }
.note.netbsd.ident : { *(.note.netbsd.ident) }
.note.openbsd.ident : { *(.note.openbsd.ident) }
/* Start of the Read Write Data region. */
/* Adjust the address for the data segment. We want to adjust up to
the same address within the page on the next page up. */
. = DATA_SEGMENT_ALIGN (CONSTANT (MAXPAGESIZE), CONSTANT (COMMONPAGESIZE));
/* Exception handling. */
.eh_frame : ONLY_IF_RW { KEEP (*(.eh_frame)) *(.eh_frame.*) }
.sframe : ONLY_IF_RW { *(.sframe) *(.sframe.*) }
.gnu_extab : ONLY_IF_RW { *(.gnu_extab) }
.gcc_except_table : ONLY_IF_RW { *(.gcc_except_table .gcc_except_table.*) }
.exception_ranges : ONLY_IF_RW { *(.exception_ranges*) }
/* Thread Local Storage sections. */
.tdata :
{
PROVIDE_HIDDEN (__tdata_start = .);
*(.tdata .tdata.* .gnu.linkonce.td.*)
}
.tbss : { *(.tbss .tbss.* .gnu.linkonce.tb.*) *(.tcommon) }
.preinit_array :
{
PROVIDE_HIDDEN (__preinit_array_start = .);
KEEP (*(.preinit_array))
PROVIDE_HIDDEN (__preinit_array_end = .);
}
.init_array :
{
PROVIDE_HIDDEN (__init_array_start = .);
KEEP (*(SORT_BY_INIT_PRIORITY(.init_array.*) SORT_BY_INIT_PRIORITY(.ctors.*)))
KEEP (*(.init_array EXCLUDE_FILE (*crtbegin.o *crtbegin?.o *crtend.o *crtend?.o ) .ctors))
PROVIDE_HIDDEN (__init_array_end = .);
}
.fini_array :
{
PROVIDE_HIDDEN (__fini_array_start = .);
KEEP (*(SORT_BY_INIT_PRIORITY(.fini_array.*) SORT_BY_INIT_PRIORITY(.dtors.*)))
KEEP (*(.fini_array EXCLUDE_FILE (*crtbegin.o *crtbegin?.o *crtend.o *crtend?.o ) .dtors))
PROVIDE_HIDDEN (__fini_array_end = .);
}
.ctors :
{
/* gcc uses crtbegin.o to find the start of
the constructors, so we make sure it is
first. Because this is a wildcard, it
doesn't matter if the user does not
actually link against crtbegin.o; the
linker won't look for a file to match a
wildcard. The wildcard also means that it
doesn't matter which directory crtbegin.o
is in. */
KEEP (*crtbegin.o(.ctors))
KEEP (*crtbegin?.o(.ctors))
/* We don't want to include the .ctor section from
the crtend.o file until after the sorted ctors.
The .ctor section from the crtend file contains the
end of ctors marker and it must be last */
KEEP (*(EXCLUDE_FILE (*crtend.o *crtend?.o ) .ctors))
KEEP (*(SORT(.ctors.*)))
KEEP (*(.ctors))
}
.dtors :
{
KEEP (*crtbegin.o(.dtors))
KEEP (*crtbegin?.o(.dtors))
KEEP (*(EXCLUDE_FILE (*crtend.o *crtend?.o ) .dtors))
KEEP (*(SORT(.dtors.*)))
KEEP (*(.dtors))
}
.jcr : { KEEP (*(.jcr)) }
.data.rel.ro : { *(.data.rel.ro.local* .gnu.linkonce.d.rel.ro.local.*) *(.data.rel.ro .data.rel.ro.* .gnu.linkonce.d.rel.ro.*) }
.dynamic : { *(.dynamic) }
.got : { *(.got) *(.igot) }
. = DATA_SEGMENT_RELRO_END (SIZEOF (.got.plt) >= 8 ? 8 : 0, .);
.got.plt : { *(.got.plt) *(.igot.plt) }
.data :
{
__DATA_BEGIN__ = .;
*(.data .data.* .gnu.linkonce.d.*)
SORT(CONSTRUCTORS)
}
.data1 : { *(.data1) }
/* We want the small data sections together, so single-instruction offsets
can access them all, and initialized data all before uninitialized, so
we can shorten the on-disk segment size. */
.sdata :
{
__SDATA_BEGIN__ = .;
*(.srodata.cst16) *(.srodata.cst8) *(.srodata.cst4) *(.srodata.cst2) *(.srodata .srodata.*)
*(.sdata .sdata.* .gnu.linkonce.s.*)
}
_edata = .;
PROVIDE (edata = .);
. = ALIGN(ALIGNOF(NEXT_SECTION));
__bss_start = .;
.sbss :
{
*(.dynsbss)
*(.sbss .sbss.* .gnu.linkonce.sb.*)
*(.scommon)
}
.bss :
{
*(.dynbss)
*(.bss .bss.* .gnu.linkonce.b.*)
*(COMMON)
/* Align here to ensure that in the common case of there only being one
type of .bss section, the section occupies space up to _end.
Align after .bss to ensure correct alignment even if the
.bss section disappears because there are no input sections.
FIXME: Why do we need it? When there is no .bss section, we do not
pad the .data section. */
. = ALIGN(. != 0 ? 32 / 8 : 1);
}
. = ALIGN(32 / 8);
/* Start of the Large Data region. */
. = SEGMENT_START("ldata-segment", .);
. = ALIGN(32 / 8);
__BSS_END__ = .;
__global_pointer$ = MIN(__SDATA_BEGIN__ + 0x800,
MAX(__DATA_BEGIN__ + 0x800, __BSS_END__ - 0x800));
_end = .;
PROVIDE (end = .);
. = DATA_SEGMENT_END (.);
/* Start of the Tiny Data region. */
/* Stabs debugging sections. */
.stab 0 : { *(.stab) }
.stabstr 0 : { *(.stabstr) }
.stab.excl 0 : { *(.stab.excl) }
.stab.exclstr 0 : { *(.stab.exclstr) }
.stab.index 0 : { *(.stab.index) }
.stab.indexstr 0 : { *(.stab.indexstr) }
.comment 0 (INFO) : { *(.comment); LINKER_VERSION; }
.gnu.build.attributes : { *(.gnu.build.attributes .gnu.build.attributes.*) }
/* DWARF debug sections.
Symbols in the DWARF debugging sections are relative to the beginning
of the section so we begin them at 0. */
/* DWARF 1. */
.debug 0 : { *(.debug) }
.line 0 : { *(.line) }
/* GNU DWARF 1 extensions. */
.debug_srcinfo 0 : { *(.debug_srcinfo) }
.debug_sfnames 0 : { *(.debug_sfnames) }
/* DWARF 1.1 and DWARF 2. */
.debug_aranges 0 : { *(.debug_aranges) }
.debug_pubnames 0 : { *(.debug_pubnames) }
/* DWARF 2. */
.debug_info 0 : { *(.debug_info .gnu.linkonce.wi.*) }
.debug_abbrev 0 : { *(.debug_abbrev) }
.debug_line 0 : { *(.debug_line .debug_line.* .debug_line_end) }
.debug_frame 0 : { *(.debug_frame) }
.debug_str 0 : { *(.debug_str) }
.debug_loc 0 : { *(.debug_loc) }
.debug_macinfo 0 : { *(.debug_macinfo) }
/* SGI/MIPS DWARF 2 extensions. */
.debug_weaknames 0 : { *(.debug_weaknames) }
.debug_funcnames 0 : { *(.debug_funcnames) }
.debug_typenames 0 : { *(.debug_typenames) }
.debug_varnames 0 : { *(.debug_varnames) }
/* DWARF 3. */
.debug_pubtypes 0 : { *(.debug_pubtypes) }
.debug_ranges 0 : { *(.debug_ranges) }
/* DWARF 5. */
.debug_addr 0 : { *(.debug_addr) }
.debug_line_str 0 : { *(.debug_line_str) }
.debug_loclists 0 : { *(.debug_loclists) }
.debug_macro 0 : { *(.debug_macro) }
.debug_names 0 : { *(.debug_names) }
.debug_rnglists 0 : { *(.debug_rnglists) }
.debug_str_offsets 0 : { *(.debug_str_offsets) }
.debug_sup 0 : { *(.debug_sup) }
.gnu.attributes 0 : { KEEP (*(.gnu.attributes)) }
/DISCARD/ : { *(.note.GNU-stack) *(.gnu_debuglink) *(.gnu.lto_*) *(.gnu_object_only) }
.others : {
*(.*)
}
__ram_start = .;
__ram_size = 0x2000000; /* 32MB */
__stack_size = 0x1000000; /* 16MB */
/* heap */
.heap : {
. = ALIGN(8);
_heap_start = .;
. = __ram_start + __ram_size - __stack_size - 1;
_heap_end = .;
}
/* stack */
.stack : {
. = ALIGN(8);
_stack_top = __ram_start + __ram_size;
. = _stack_top - __stack_size;
*(.stack)
. = _stack_top;
}
}
You may experience some issue about global pointer, so you may need to change its defination,
or disable it through -Wl,--no-relax-gp
About the stub functions for newlib,
#include <errno.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#define SYS_read 63
#define SYS_write 64
#define SYS_exit 93
#ifdef __cplusplus
#define EXTERN_C_BEGIN \
extern "C" \
{
#define EXTERN_C_END }
#else
#define EXTERN_C_BEGIN
#define EXTERN_C_END
#endif
extern char _heap_start;
extern char _heap_end;
static char *heap_end = &_heap_start;
EXTERN_C_BEGIN
caddr_t _sbrk(int incr)
{
char *prev;
if (heap_end + incr > &_heap_end)
{
errno = ENOMEM;
return (caddr_t)-1;
}
prev = heap_end;
heap_end += incr;
return prev;
}
int _write(int fd, char *ptr, int len)
{
register int a0 asm("a0") = fd;
register int a1 asm("a1") = (int)ptr;
register int a2 asm("a2") = len;
register int a7 asm("a7") = SYS_write;
asm volatile("ecall"
: "+r"(a0)
: "r"(a1), "r"(a2), "r"(a7)
: "memory");
return a0;
}
int _fstat(int fd, struct stat *sb)
{
if (fd >= 0 && fd <= 1)
{
// stdin, stdout, stderr(not supported)
sb->st_mode = S_IFCHR;
return 0;
}
errno = EBADF;
return -1;
}
int _isatty(int fd)
{
return 1; // always true for a character device
}
int _lseek(int fd, off_t offset, int whence)
{
return 0; // not supported
}
int _close(int fd)
{
return -1; // not supported
}
int _read(int fd, char *ptr, int len)
{
register int a0 asm("a0") = fd;
register int a1 asm("a1") = (int)ptr;
register int a2 asm("a2") = len;
register int a7 asm("a7") = SYS_read;
asm volatile("ecall"
: "+r"(a0)
: "r"(a1), "r"(a2), "r"(a7)
: "memory");
return a0;
}
void _exit(int status)
{
register int a0 asm("a0") = status;
register int a7 asm("a7") = SYS_exit;
asm volatile("ecall"
:
: "r"(a0), "r"(a7)
: "memory");
while (1)
; // halt the CPU
}
int _kill(int pid, int sig)
{
errno = EINVAL;
return -1;
}
int _getpid(void)
{
return 1;
}
int _open(const char *name, int flags, int mode)
{
errno = ENOENT; // do not support any files, so it does not exist
return -1;
}
EXTERN_C_END
And don't forget to set the stack pointer in the custom entry,
.section .vectors, "ax"
.globl _vectors
_vectors:
# load _stack_top to sp
lui sp, %hi(_stack_top) # load high 20 bits
addi sp, sp, %lo(_stack_top) # add low 12 bits
j _start
Enjoy your new environment!