The full start-up sequence (TPL->SPL->U-Boot) can be a bit confusing since each phase has its own 'start' file. Add comments to explain this.
Signed-off-by: Simon Glass sjg@chromium.org ---
arch/x86/cpu/start.S | 12 ++++++++++++ arch/x86/cpu/start_from_spl.S | 5 +++-- arch/x86/cpu/start_from_tpl.S | 3 ++- 3 files changed, 17 insertions(+), 3 deletions(-)
diff --git a/arch/x86/cpu/start.S b/arch/x86/cpu/start.S index 9b76394274..01524635e9 100644 --- a/arch/x86/cpu/start.S +++ b/arch/x86/cpu/start.S @@ -2,6 +2,18 @@ /* * U-Boot - x86 Startup Code * + * This is always the first code to run from the U-Boot source. To spell it out: + * + * 1. When TPL (Tertiary Program Loader) is enabled, the boot flow is + * TPL->SPL->U-Boot and this file is used for TPL. Then start_from_tpl.S is used + * for SPL and start_from_spl.S is used for U-Boot proper. + * + * 2. When SPL (Secondary Program Loader) is enabled, but not TPL, the boot + * flow is SPL->U-Boot and this file is used for SPL. Then start_from_spl.S is + * used for U-Boot proper. + * + * 3. When neither TPL nor SPL is used, this file is used for U-Boot proper. + * * (C) Copyright 2008-2011 * Graeme Russ, graeme.russ@gmail.com * diff --git a/arch/x86/cpu/start_from_spl.S b/arch/x86/cpu/start_from_spl.S index 4d4e5d0758..a73b4d7c45 100644 --- a/arch/x86/cpu/start_from_spl.S +++ b/arch/x86/cpu/start_from_spl.S @@ -1,7 +1,8 @@ /* SPDX-License-Identifier: GPL-2.0+ */ /* - * 32-bit x86 Startup Code when running from SPL - * + * 32-bit x86 Startup Code when running from SPL. This is the startup code in + * U-Boot proper, when SPL is used. + * Copyright 2018 Google, Inc * Written by Simon Glass sjg@chromium.org */ diff --git a/arch/x86/cpu/start_from_tpl.S b/arch/x86/cpu/start_from_tpl.S index 44b5363a68..9a4974a5f1 100644 --- a/arch/x86/cpu/start_from_tpl.S +++ b/arch/x86/cpu/start_from_tpl.S @@ -1,6 +1,7 @@ /* SPDX-License-Identifier: GPL-2.0+ */ /* - * 32-bit x86 Startup Code when running from TPL + * 32-bit x86 Startup Code when running from TPL. This is the startup code in + * SPL, when TPL is used. * * Copyright 2018 Google, Inc * Written by Simon Glass sjg@chromium.org