From b28b8ac0d2ac99b99362d6052af9a507757469c9 Mon Sep 17 00:00:00 2001 From: Abner Chang <abner.chang@hpe.com> Date: Wed, 8 Jan 2020 12:54:34 +0800 Subject: docs: Add description of using OPENSBI_EXTERNAL_SBI_TYPES Add description of using OPENSBI_EXTERNAL_SBI_TYPES in external firmware code base. Signed-off-by: Abner Chang <abner.chang@hpe.com> Cc: Leif Lindholm <leif.lindholm@linaro.org> Reviewed-by: Anup Patel <anup.patel@wdc.com> --- docs/library_usage.md | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'docs') diff --git a/docs/library_usage.md b/docs/library_usage.md index d765fa9..ff99801 100644 --- a/docs/library_usage.md +++ b/docs/library_usage.md @@ -66,3 +66,24 @@ bootloader to service the following interrupts and traps: **Note:** external firmwares or bootloaders can be more conservative by forwarding all traps and interrupts to *sbi_trap_handler()*. + +Definitions of OpenSBI Data Types for the External Firmware +----------------------------------------------------------- + +OpenSBI can be built as library using external firmware build system such as EDK2 +code base (The open source of UEFI firmware implementation) and linked with external +firmware drivers based on the external firmware architecture. + +**OPENSBI_EXTERNAL_SBI_TYPES** identifier is introduced to *sbi_types.h* for selecting +external header file during the build preprocess in order to define OpensSBI data types +based on external firmware data type binding. +For example, *bool* is declared as *int* in sbi_types.h. However in EDK2 build system, +*bool* is declared as *BOOLEAN* which is defined as *unsigned char* data type. + +External firmware can define **OPENSBI_EXTERNAL_SBI_TYPES** in CFLAGS and specify it to the +header file maintained in its code tree. However, the external build system has to address +the additional include directory for the external header file based on its own build system. +For example, +*-D***OPENSBI_EXTERNAL_SBI_TYPES***=OpensbiTypes.h* +Above tells *sbi_types.h* to refer to *OpensbiTypes.h* instead of using original definitions of +data types. -- cgit v1.2.3