From: Aaron Sierra asierra@xes-inc.com
Some OSes require that secondary cores not be initialized when they are booted (eg VxWorks). By default when U-Boot is compiled with the CONFIG_MP option all secondary cores are brought out of reset and held in spinloops. Setting the "mp_holdoff" environment variable to a non-null value will cause U-Boot to leave secondary cores in their default state.
Signed-off-by: Aaron Sierra asierra@xes-inc.com Signed-off-by: Peter Tyser ptyser@xes-inc.com --- arch/powerpc/cpu/mpc85xx/mp.c | 18 ++++++++++++++++++ 1 files changed, 18 insertions(+), 0 deletions(-)
diff --git a/arch/powerpc/cpu/mpc85xx/mp.c b/arch/powerpc/cpu/mpc85xx/mp.c index 603baef..7ad5efb 100644 --- a/arch/powerpc/cpu/mpc85xx/mp.c +++ b/arch/powerpc/cpu/mpc85xx/mp.c @@ -51,6 +51,11 @@ int cpu_status(int nr) { u32 *table, id = get_my_id();
+ if (getenv("mp_holdoff")) { + printf("Secondary cores are disabled; mp_holdoff is set\n"); + return 0; + } + if (nr == id) { table = (u32 *)get_spin_virt_addr(); printf("table base @ 0x%p\n", table); @@ -133,6 +138,11 @@ int cpu_release(int nr, int argc, char * const argv[]) u32 i, val, *table = (u32 *)get_spin_virt_addr() + nr * NUM_BOOT_ENTRY; u64 boot_addr;
+ if (getenv("mp_holdoff")) { + printf("Secondary cores are disabled; mp_holdoff is set\n"); + return 0; + } + if (nr == get_my_id()) { printf("Invalid to release the boot core.\n\n"); return 1; @@ -353,6 +363,14 @@ void setup_mp(void) ulong fixup = (ulong)&__secondary_start_page; u32 bootpg = determine_mp_bootpg();
+ /* + * Some OSes expect the secondary cores to be held in reset when the OS + * boots. Use the optional 'mp_holdoff' environment variable to allow + * users to disable the bring up of secondary cores. + */ + if (getenv("mp_holdoff")) + return; + /* Store the bootpg's SDRAM address for use by secondary CPU cores */ __bootpg_addr = bootpg;