On Thursday 29 July 2010 10:40:49 am Theo Debrouwere wrote:
> > But my favourite optimization was removing u-boot completely and booting
> > Linux kernel from ubl directly. Though this is not an option for
> > everyone.
>
> What did you do for this? Any UBL patch available to take a look at?
>
There was an C example at [1] which I stole most of the bits but I can not
find that example at the moment. I attached my code to the end of this e-mail.
Then all I need to do is call following from ubl.c:
extern int start_linux(void); start_linux();
If you want to look at my complete UBL, I can send it to you privately.(not to
waste list bw) I have a local git tree for that. In my tree I have LCD and
EDMA support for UBL as well. But my tree is for a custom DM6446 board, no EVM
support in it.
Regards,
Caglar
[1] http://www.arm.linux.org.uk/developer/booting.php
> Theo
>
>
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#include "config.h"
/* list of possible tags */
#define ATAG_NONE 0x00000000
#define ATAG_CORE 0x54410001
#define ATAG_MEM 0x54410002
#define ATAG_VIDEOTEXT 0x54410003
#define ATAG_RAMDISK 0x54410004
#define ATAG_INITRD2 0x54420005
#define ATAG_SERIAL 0x54410006
#define ATAG_REVISION 0x54410007
#define ATAG_VIDEOLFB 0x54410008
#define ATAG_CMDLINE 0x54410009
#define u32_t unsigned int
#define u32 unsigned int
#define u16 unsigned short
#define u8 unsigned char
/* structures for each atag */
struct atag_header {
u32 size; /* length of tag in words including this header */
u32 tag; /* tag type */
};
struct atag_core {
u32 flags;
u32 pagesize;
u32 rootdev;
};
struct atag_mem {
u32 size;
u32 start;
};
struct atag_videotext {
u8 x;
u8 y;
u16 video_page;
u8 video_mode;
u8 video_cols;
u16 video_ega_bx;
u8 video_lines;
u8 video_isvga;
u16 video_points;
};
struct atag_ramdisk {
u32 flags;
u32 size;
u32 start;
};
struct atag_initrd2 {
u32 start;
u32 size;
};
struct atag_serialnr {
u32 low;
u32 high;
};
struct atag_revision {
u32 rev;
};
struct atag_videolfb {
u16 lfb_width;
u16 lfb_height;
u16 lfb_depth;
u16 lfb_linelength;
u32 lfb_base;
u32 lfb_size;
u8 red_size;
u8 red_pos;
u8 green_size;
u8 green_pos;
u8 blue_size;
u8 blue_pos;
u8 rsvd_size;
u8 rsvd_pos;
};
struct atag_cmdline {
char cmdline[1];
};
struct atag {
struct atag_header hdr;
union {
struct atag_core core;
struct atag_mem mem;
struct atag_videotext videotext;
struct atag_ramdisk ramdisk;
struct atag_initrd2 initrd2;
struct atag_serialnr serialnr;
struct atag_revision revision;
struct atag_videolfb videolfb;
struct atag_cmdline cmdline;
} u;
};
#define tag_next(t) ((struct atag *)((u32 *)(t) + (t)->hdr.size))
#define tag_size(type) ((sizeof(struct atag_header) + sizeof(type)) >> 2)
static struct atag *params; /* used to point at the current tag */
static void
setup_core_tag(void * address,long pagesize)
{
params = (struct atag *)address; /* Initialise parameters to start at given address */
params->hdr.tag = ATAG_CORE; /* start with the core tag */
params->hdr.size = tag_size(struct atag_core); /* size the tag */
params->u.core.flags = 1; /* ensure read-only */
params->u.core.pagesize = pagesize; /* systems pagesize (4k) */
params->u.core.rootdev = 0; /* zero root device (typicaly overidden from commandline )*/
params = tag_next(params); /* move pointer to next tag */
}
static void
setup_mem_tag(u32_t start, u32_t len)
{
params->hdr.tag = ATAG_MEM; /* Memory tag */
params->hdr.size = tag_size(struct atag_mem); /* size tag */
params->u.mem.start = start; /* Start of memory area (physical address) */
params->u.mem.size = len; /* Length of area */
params = tag_next(params); /* move pointer to next tag */
}
u32 strlen(const char *s)
{
const char *sc;
for (sc = s; *sc != '\0'; ++sc)
/* nothing */;
return sc - s;
}
char *strncpy(char *dest, const char *src, u32 count)
{
char *tmp = dest;
while (count) {
if ((*tmp = *src) != 0)
src++;
tmp++;
count--;
}
return dest;
}
static void
setup_cmdline_tag(const char * line)
{
int linelen = strlen(line);
if(!linelen)
return; /* do not insert a tag for an empty commandline */
params->hdr.tag = ATAG_CMDLINE; /* Commandline tag */
params->hdr.size = (sizeof(struct atag_header) + linelen + 1 + 4) >> 2;
strncpy(params->u.cmdline.cmdline, line, linelen); /* place commandline into tag */
params = tag_next(params); /* move pointer to next tag */
}
static void
setup_end_tag(void)
{
params->hdr.tag = ATAG_NONE; /* Empty tag ends list */
params->hdr.size = 0; /* zero length */
}
#define DRAM_BASE 0x80000000
#define IMAGE_LOAD_ADDRESS DRAM_BASE + 0x8000
#define MACH_TYPE_DAVINCI_BEGINNING 1849
static void
setup_tags(u32 parameters)
{
setup_core_tag((void *)parameters, 4096); /* standard core tag 4k pagesize */
setup_mem_tag(DRAM_BASE, 0x10000000); /* 64Mb at 0x10000000 */
setup_cmdline_tag(CMDLINE); /* commandline setting root device */
setup_end_tag(); /* end of tags */
}
int
start_linux(void)
{
void (*theKernel)(int zero, int arch, u32 params);
u32 exec_at = (u32)-1;
u32 parm_at = (u32)-1;
u32 machine_type;
exec_at = IMAGE_LOAD_ADDRESS;
parm_at = DRAM_BASE + 0x100;
//load_image(name, exec_at); /* copy image into RAM */
setup_tags(parm_at); /* sets up parameters */
machine_type = MACH_TYPE_DAVINCI_BEGINNING; /* get machine type */
theKernel = (void (*)(int, int, u32))exec_at; /* set the kernel address */
theKernel(0, machine_type, parm_at); /* jump to kernel with register set */
return 0;
}_______________________________________________
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