Kconfig add config ERR_PTR_OFFSET

Some U-Boot pointers have redundant information, so we can use a scheme
where we can return either an error code or a pointer with the same
return value. The default implementation just casts the pointer to a
number, however, this may fail on platforms where the end of the address
range is used for valid pointers (e.g. 0xffffff00 is a valid heap pointer
in socfpga SPL). For such platforms, this value provides an upper range
of those error pointer values - up to 'MAX_ERRNO' bytes below this value
must be unused/invalid addresses.

Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>

diff --git a/Kconfig b/Kconfig
index 66b059f..cda4f58 100644 (file)
--- a/Kconfig
+++ b/Kconfig
@@ -281,6 +281,20 @@ config SYS_LDSCRIPT
          Path within the source tree to the linker script to use for the
          main U-Boot binary.
 
+config ERR_PTR_OFFSET
+       hex
+       default 0x0
+       help
+         Some U-Boot pointers have redundant information, so we can use a
+         scheme where we can return either an error code or a pointer with the
+         same return value. The default implementation just casts the pointer
+         to a number, however, this may fail on platforms where the end of the
+         address range is used for valid pointers (e.g. 0xffffff00 is a valid
+         heap pointer in socfpga SPL).
+         For such platforms, this value provides an upper range of those error
+         pointer values - up to 'MAX_ERRNO' bytes below this value must be
+         unused/invalid addresses.
+
 endmenu                # General setup
 
 menu "Boot images"