compile on command line about gcc-ia16 HOT 19 CLOSED

Hello @georgp24,

Use the -melks switch to compile for ELKS --- gcc-ia16 compiles for MS-DOS on default. For now you also need to specify -mcmodel=small to compile for the small memory model (but I hope to remove this need for ELKS).

You should not need the -I... switch.

Thank you!

from gcc-ia16.

Hi @tkchia,

I still do not get to compile, I just run the env.sh script in elks and this apparently does not set the paths as required. So I have to add the -I switch or it will not find stdio.h. Now I tried:
~/elks> ia16-elf-gcc hello.c -o hello -Icross/ia16-elf/lib/elkslibc/include -melks -mcmodel=small
It now says: Linkerscript »elk-mssl.ld« missing

from gcc-ia16.

Hello @georgp24,

My apologies... the options should be -melks-libc -mcmodel=small. Please let me know if you encounter any further problems.

(-melks will currently link with the Newlib C library for ELKS, but I am in the process of dropping support for that, in favour of ELKS's own C library.)

Thank you!

from gcc-ia16.

Hi tkchia,
thank you! I could compile my hello world program now and got it to run on ELKS.

Now I try to compile an assembler program with these commands:
ia16-elf-gcc -c hello.S
ia16-elf-ld hello.o -o hello
This generates a program that works on my Linux system but not with ELKS. What needs to be done here?

from gcc-ia16.

Hello @georgp24,

You can also use ia16-elf-gcc for the linking step (it will pass the correct linker script etc. to ia16-elf-ld):

ia16-elf-gcc hello.o -o hello

If you want to exclude the system startup files and/or libraries from the link, use the -nostdlib or -nodefaultlibs option (see the GCC documentation). Thank you!

from gcc-ia16.

I forgot: also add -melks-libc -mcmodel=small to the GCC command lines. Thank you!

from gcc-ia16.

I tried these lines:

ia16-elf-gcc -c hello.S -mcmodel=small -melks-libc
ia16-elf-gcc -c hello.o -o helloa -nodefaultlibs

In the linking step it reports the warning that: 'the input files of the linker will be used because no linking takes place'. No executable is generated.

This is the code:

.text                            # section declaration
 		                   # we must export the entry point to the ELF linker or
.global _start                # loader. They conventionally recognize _start as their
			            # entry point. Use ld -e foo to override the default.
_start:
                                    # write our string to stdout
	  movl    $len,%edx           # third argument: message length
	  movl    $msg,%ecx          # second argument: pointer to message to write
	  movl    $1,%ebx             # first argument: file handle (stdout)
	  movl    $4,%eax             # system call number (sys_write)
	  int     $0x80                   # call kernel and exit

	  movl    $0,%ebx             # first argument: exit code
	  movl    $1,%eax             # system call number (sys_exit)
	  int     $0x80                 # call kernel
.data                             # section declaration
msg:
	.ascii    "Hello, world!\n"   # our dear string
       len = . - msg                   # length of our dear string

from gcc-ia16.

OK, the link line should rather be:
ia16-elf-gcc hello.o -o helloa -nodefaultlibs
now I get the problem: Linkerscript »dos-mts.ld« cannot be found.

from gcc-ia16.

Meanwhile I tried:
ia16-elf-ld hello.o -o helloa -nodefaultlibs
This generates a program called defaultlibs which can be executed with Linux and outputs "Hello world". Then I tried:
ia16-elf-ld hello.o -nodefaultlibs -o helloa
This generates a program called helloa that runs on Linux but not on ELKS.

from gcc-ia16.

Helo @georgp24,

There are several things:

• You need to specify -melks-libc -mcmodel=small both at compilation time (-c) and at link time.
• You need to specify .code16 near the start of the assembly source so that GNU as will assemble instructions in 16-bit mode (this is a bit unfortunate, and I hope to fix this some day).
• The "true" entry point is currently called entry, not _start, in ELKS's C library linker scripts (perhaps this should also be fixed...). [edit: I have sent in a pull request to ELKS to fix this.]
• Also, -nostdlib rather than -nodefaultlibs is probably what you need, if you also want to leave out the program startup module (crt0.o).
• There is no need to set 32-bit registers %eax etc. when making syscalls. The ELKS kernel --- which can also run on 16-bit-only machines --- only cares about the contents of the 16-bit registers %ax, %bx, %cx, etc.

Therefore:

$ cat hello.S
	.code16

	.text

	.global	entry
entry:
	movw	$len,%dx
	movw	$msg,%cx
	movw	$1,%bx
	movw	$4,%ax
	int	$0x80

	movw	$0,%bx
	movw	$1,%ax
	int	$0x80

	.data
msg:
	.ascii	"Hello, world\n"
	len = . - msg
$ ia16-elf-gcc -melks-libc -mcmodel=small -c hello.S -o hello.o
$ ia16-elf-gcc -melks-libc -mcmodel=small -nostdlib hello.o -o helloa

Thank you!

from gcc-ia16.

Hello @georgp24,

Another tip: if you build the whole ELKS tree, there will also be a program elksemu which can run an ELKS program under Linux/x86-32 or Linux/x86-64. This should be under elksemu/elksemu. You can use this program to quickly test your ELKS programs on Linux before moving them onto a real ELKS system.

$ ./helloa
bash: ./helloa: cannot execute binary file: Exec format error
$ ....../elksemu helloa
Hello, world

Thank you!

from gcc-ia16.

Hello @georgp24, let me know if you still have any questions. Thank you!

from gcc-ia16.

Thank you very much tkchia, I got it working now!
I saw in the linker script that you also support the tiny model. Does this work too?

from gcc-ia16.

I also tried elksemu as you mentioned.
elksemu/elksemu ./helloa
This did just output:
waitpid failed

from gcc-ia16.

Hello @georgp24,

Thank you very much tkchia, I got it working now!

No problem. :-)

I saw in the linker script that you also support the tiny model. Does this work too?

The newer ELKS kernel unfortunately does not run tiny model programs --- so you can try to compile a program for the tiny model, but it will not run.

This did just output:
waitpid failed

This is strange. What is the output of strace on elksemu? I.e.

strace elksemu/elksemu ./helloa

Thank you!

from gcc-ia16.

I tried Intel syntax with as. Is it correct that gcc-ia16 does not support the -mnaked-reg parameter?

Here is the strace output:

ia16-elf-gcc: Fehler: nicht erkannte Kommandozeilenoption »-mnaked-reg«
georg@linux-lj8b:~/elks> strace elksemu/elksemu ./helloa
execve("elksemu/elksemu", ["elksemu/elksemu", "./helloa"], [/* 103 vars */]) = 0
brk(0)                                  = 0x1a7e000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f610d21a000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=154583, ...}) = 0
mmap(NULL, 154583, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f610d1f4000
close(3)                                = 0
open("/lib64/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\0\10\2\0\0\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1925032, ...}) = 0
mmap(NULL, 3811776, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f610cc58000
mprotect(0x7f610cdf1000, 2097152, PROT_NONE) = 0
mmap(0x7f610cff1000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x199000) = 0x7f610cff1000
mmap(0x7f610cff7000, 14784, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f610cff7000
close(3)                                = 0
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f610d1f3000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f610d1f2000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f610d1f1000
arch_prctl(ARCH_SET_FS, 0x7f610d1f2700) = 0
mprotect(0x7f610cff1000, 16384, PROT_READ) = 0
mprotect(0x605000, 4096, PROT_READ)     = 0
mprotect(0x7f610d21b000, 4096, PROT_READ) = 0
munmap(0x7f610d1f4000, 154583)          = 0
access("./helloa", X_OK)                = 0
open("./helloa", O_RDONLY)              = 3
fstat(3, {st_mode=S_IFREG|0755, st_size=77, ...}) = 0
getuid()                                = 1000
getgid()                                = 100
setregid(100, 100)                      = 0
setreuid(1000, 1000)                    = 0
modify_ldt(0, 0x7fff9585af60, 0x10000)  = 0
modify_ldt(0x1, 0x7fff9585af50, 0x10)   = 0
modify_ldt(0x1, 0x7fff9585af40, 0x10)   = 0
mmap(NULL, 135168, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_ANONYMOUS|MAP_32BIT, -1, 0) = 0x4021f000
mprotect(0x4023f000, 4096, PROT_NONE)   = 0
read(3, "\1\0030\4 \0\0\0 \0\0\0\r\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 32) = 32
read(3, "f\272\r\0\0\0f\271\0\0\0\0f\273\1\0\0\0\270\4\0\315\200\273\0\0\270\1\0\315\200\220", 32) = 32
read(3, "Hello, world\n", 13)           = 13
modify_ldt(0x1, 0x7fff9586af70, 0x10)   = 0
modify_ldt(0x1, 0x7fff9586af80, 0x10)   = 0
close(3)                                = 0
clone(child_stack=0x4022e10e, flags=CLONE_VM|CLONE_FS|CLONE_FILES|CLONE_IO) = 3195
ptrace(PTRACE_ATTACH, 3195, 0, 0)       = 0
--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_TRAPPED, si_pid=3195, si_status=SIGSTOP, si_utime=0, si_stime=0} ---
wait4(3195, 0x7fff9586aebc, 0, NULL)    = -1 ECHILD (No child processes)
write(2, "waitpid failed\n", 15waitpid failed
)        = 15
exit_group(255)                         = ?
+++ exited with 255 +++
georg@linux-lj8b:~/elks> sudo mount -o loop image/fd1440.bin floppy1
root's password:
georg@linux-lj8b:~/elks> sudo cp ./helloa floppy1/usr/bin
georg@linux-lj8b:~/elks> ./qemu.sh

(process:3212): GLib-WARNING **: gmem.c:483: custom memory allocation vtable not supported
char device redirected to /dev/pts/2 (label chardev1)
Warning: default mac address being used, creating potential for address conflict

from gcc-ia16.

The newer ELKS kernel unfortunately does not run tiny model program --- so you can try to >compile a program for the tiny model, but it will not run.

I looked at the program loader about three years ago. It had code to run tiny model programs but that did not work and I did not get it to work.

from gcc-ia16.

Hello @georgp24,

I tried Intel syntax with as. Is it correct that gcc-ia16 does not support the -mnaked-reg parameter?

The GCC front end does not understand this option --- only the assembler does. So you need to wrap it in -Wa,... e.g. -Wa,-mnaked-reg or -Wa,-msyntax=INTEL etc.

Alternatively, you can write a pseudo-op inside the .S source file itself, e.g.

.intel_syntax

or

.intel_syntax noprefix

etc.

ptrace(PTRACE_ATTACH, 3195, 0, 0)       = 0
--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_TRAPPED, si_pid=3195, si_status=SIGSTOP, si_utime=0, si_stime=0} ---
wait4(3195, 0x7fff9586aebc, 0, NULL)    = -1 ECHILD (No child processes)

The ECHILD error is strange. I am unfortunately still unable to reproduce this problem on my end. Meanwhile I think I will help you open an issue report for this on the ELKS project.

Thank you!

from gcc-ia16.

I tried Intel syntax with as. Is it correct that gcc-ia16 does not support the -mnaked-reg parameter?

-masm=intel is the switch you're looking for.

edit: To make gcc emit intel asm, that is. For assembling I think .intel_syntax noprefix is the best option.

from gcc-ia16.