Hello all, I write due to a big question I have. I am using a custom board of imx6 with a custom bootloader and I am trying to copy the zimage from pnor to ram. There is no problem copy the information and then I want to jump to the memory address of the kernel to start its execution but it doesn work.
I found this same process in the u-boot file like the following:
int do_sh_zimageboot (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
{
ulong (*zboot_entry)(int, char * const []) = NULL;
char *s0, *s1;
unsigned char *param = NULL;
char *cmdline;
char *bootargs;
disable_interrupts();
if (argc >= 3) {
/* argv[1] holds the address of the zImage */
s0 = argv[1];
/* argv[2] holds the address of zero page */
s1 = argv[2];
} else {
goto exit;
}
if (s0)
zboot_entry = (ulong (*)(int, char * const []))simple_strtoul(s0, NULL, 16);
/* empty_zero_page */
if (s1)
param = (unsigned char*)simple_strtoul(s1, NULL, 16);
/* Linux kernel command line */
cmdline = (char *)param + COMMAND_LINE;
bootargs = getenv("bootargs");
/* Clear zero page */
/* cppcheck-suppress nullPointer */
memset(param, 0, 0x1000);
/* Set commandline */
strcpy(cmdline, bootargs);
/* Boot */
zboot_entry(0, NULL);
exit:
return -1;
}
So if the address of my kernel is 0x4000000 how should I jump to that address? Can someone explain me how this is working to do the jump?
zboot_entry = (ulong (*)(int, char * const []))simple_strtoul(s0, NULL, 16);
In internet i found this to jump to a memory address:
unsigned long address=0x80;
void (*func_ptr)(void) = (void (*)(void))address;
func_ptr();
but how exactly does it work?
Thanks for the help.
