From 90b7caaf55acbe521d690453a02282e665ad3399 Mon Sep 17 00:00:00 2001 From: Stephen Warren Date: Tue, 10 Mar 2015 15:40:58 -0600 Subject: config_distro_bootcmd.h: add note on error handling This should make it more clear why there appear to be C pre-processor symbols in the file that contain mixed case. They're really error messages. Suggested-by: Simon Glass Signed-off-by: Stephen Warren Reviewed-by: Tom Rini Reviewed-by: Simon Glass --- include/config_distro_bootcmd.h | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/include/config_distro_bootcmd.h b/include/config_distro_bootcmd.h index 07a0b3b234..73f093f9ea 100644 --- a/include/config_distro_bootcmd.h +++ b/include/config_distro_bootcmd.h @@ -10,6 +10,22 @@ #ifndef _CONFIG_CMD_DISTRO_BOOTCMD_H #define _CONFIG_CMD_DISTRO_BOOTCMD_H +/* + * A note on error handling: It is possible for BOOT_TARGET_DEVICES to + * reference a device that is not enabled in the U-Boot configuration, e.g. + * it may include MMC in the list without CONFIG_CMD_MMC being enabled. Given + * that BOOT_TARGET_DEVICES is a macro that's expanded by the C pre-processor + * at compile time, it's not possible to detect and report such problems via + * a simple #ifdef/#error combination. Still, the code needs to report errors. + * The best way I've found to do this is to make BOOT_TARGET_DEVICES expand to + * reference a non-existent symbol, and have the name of that symbol encode + * the error message. Consequently, this file contains references to e.g. + * BOOT_TARGET_DEVICES_references_MMC_without_CONFIG_CMD_MMC. Given the + * prevalence of capitals here, this looks like a pre-processor macro and + * hence seems like it should be all capitals, but it's really an error + * message that includes some other pre-processor symbols in the text. + */ + /* We need the part command */ #define CONFIG_PARTITION_UUIDS #define CONFIG_CMD_PART -- cgit v1.2.1