Re: [MiNT] Patch for xaloader.prg

[Peter Persson <pep.fishmoose@gmail.com>]

On 1 mar 2010, at 22.38, Miro Kropacek wrote:
> This whole thing can be taken for much wider purpose -- I remember discussion with Frank, he told me the best solution for VM-ready mint kernel would be separate memory (and other) initializations into one small loader, i.e. set up everything incl. MMU (read-only text segments for all loaded TSRs for example) and then just load kernel itself to completely safe/sane environment. So definitely go ahead Peter, your work can be very good base for this extension in a future.
> 
> About the menu: yes, I'd welcome it very much, looking into <sysdir> for all possible *.PRG files would be awesome -- remember not only CPU but also things like debug kernels or custom configurations are quite nice to be selectable.

I definitely agree with all this, but right now I'll prefer doing something which can be used "today" :)

I've written a loader which loads kernel binaries from /mint/ and allows the kernel to process the remainder of the auto folder (some ugly DTA magic was needed, but it's the same ugly magic that's already in the kernel init code (init.c, get_my_name()).

This is not a patch or diff, but it's written in the same manner as xaloader.prg, and could be useful to more people than myself. If my coding style isn't too horrible it could perhaps be part of the kernel distro. I don't know the proper procedure for this, but I've included the code below (it uses the same "skeleton" as xaloader.prg):


#include <mint/cookie.h>
#include <mint/basepage.h>
#include <mint/mintbind.h>
#include <mint/ssystem.h>
#include <sys/fcntl.h>
#include <string.h>

/* cookie jar definition
 */
typedef struct
{
	long id;
	long value;
} COOKIE;

#define CJAR	(*(struct cookie *)(0x5A0))

#define MINTDIR	       "c:\\mint"
#define DEFAULT        "mint.prg"
#define DEFAULT_68000  "mint000.prg"
#define DEFAULT_68020  "mint020.prg"
#define DEFAULT_68030  "mint030.prg"
#define DEFAULT_68040  "mint040.prg"
#define DEFAULT_68060  "mint060.prg"
#define DEFAULT_MILAN  "mintmil.prg"
#define DEFAULT_ARANYM "mintara.prg"

long
get_cookie (long id, unsigned long *ret)
{
	void *oldssp;
	COOKIE *cjar;
	
	oldssp = (Super(1L) ? NULL : Super(0L));
	
	cjar = *(COOKIE**)(0x5A0);
	
	if(oldssp)
		Super( oldssp );
	
	while (cjar->id)
	{
		if (cjar->id == id)
		{
			if (ret)
			{
				*ret = cjar->value;
				return 1;
			}
			else
			{
				return cjar->value;
			}
		}
		
		cjar++;
	}
	
	return 0;
}


static void
my_strlcpy(char *dst, const char *src, size_t n)
{
	size_t org_n = n;
	
	if (n && --n)
	{
		do {
			if (!(*dst++ = *src++))
				break;
		}
		while (--n);
		
	}
	
	if (org_n && n == 0)
		*dst = '\0';
}

static void
my_strlcat(char *dst, const char *src, size_t n)
{
	if (!n)
		return;
	
	/* find end */
	while (n-- && *dst)
		dst++;
	
	/* copy over */
	if (n && --n)
	{
		do {
			if (!(*dst++ = *src++))
				break;
		}
		while (--n);
		
	}
	
	/* terminate */
	if (n == 0)
		*dst = '\0';
}

int loader_init(int argc, char **argv, char **env);

int
loader_init(int argc, char **argv, char **env)
{
	BASEPAGE *bp;
	long cpu, mch;
	char path[384];
	char temp[384];
	char *name;
	long fh, r;
	
	Cconws("FreeMiNT loader starting...\r\n");
	
	my_strlcpy(path, MINTDIR, sizeof(path));
	
	
	/* if the system have a 68000 CPU we use the 68000 compiled
	 * kernel by default
	 */
	r = get_cookie(C__CPU, &cpu);
	if (r && cpu < 20)
		name = DEFAULT_68000;
	else
		name = DEFAULT;
	
	my_strlcpy(temp, path, sizeof(path));		
	my_strlcat(temp, "\\", sizeof(temp));
	my_strlcat(temp, name, sizeof(temp));
	
	fh = Fopen(temp, O_RDONLY);
	if (fh < 0)
	{
		/* default kernel not available, select kernel based on CPU type */
		if(get_cookie(C__CPU, &cpu))
		{
			switch(cpu)
			{
				case 20:	name = DEFAULT_68020;	break;
				case 30:	name = DEFAULT_68030;	break;
				case 40:	name = DEFAULT_68040;	break;
				case 60:	name = DEFAULT_68060;	break;
					
				default:	break;
			}
		}
		
		/* special treatment for MILAN and ARANYM */
		if(get_cookie(C__MCH, &mch))
		{
			switch(mch>>16)
			{
				case 4:	name = DEFAULT_MILAN;	break;
				case 5: name = DEFAULT_ARANYM;	break;
			}
		}
	}
	
	Fclose((int)fh);	
	
	/* append kernel name */
	my_strlcat(path, "\\", sizeof(path));
	my_strlcat(path, name, sizeof(path));
	
	/* check if file exist */
	fh = Fopen(path, O_RDONLY);
	if (fh < 0)
	{
		Cconws("FreeMiNT loader: No such file: \"");
		Cconws(path);
		Cconws("\"\r\n");
		goto error;
	}
	Fclose((int)fh);
	
	Cconws("Load kernel: ");
	Cconws(path);
	Cconws("\r\n");

	/*
	 * Let our DTA point to our parent DTA; the kernel use
	 * information from the DTA when processing the auto folder
	 */
	 
	if(_base->p_parent)
		Fsetdta((_DTA*) _base->p_parent->p_dta);
	
	if(Pexec(0, path, 0, 0))
	{
		Cconws("FreeMiNT loader: Pexec() failed!\r\n");
		goto error;
	}
	return 0;
	
error:
	Cconws("press any key to continue ...\r\n");
	Cconin();
	return 1;
}