Store the 'compatibility revision' number in the top 4 bits of the machine id and pass it to the kernel. The old buggy kernels will fail to load with a very much googlable error message on the serial console:
"Error: unrecognized/unsupported machine ID (r1 = 0x100010bb)"
This error message can be documented in the linux-sunxi wiki with proper explanations about how to resolve this situation and where to get the necessary bugfixes for the sunxi-3.4 kernel.
The fixed sunxi-3.4 kernels can implement a revision compatibility check and clear the top 4 bits of the machine id if everything is alright.
Signed-off-by: Siarhei Siamashka siarhei.siamashka@gmail.com ---
To be used together with: https://groups.google.com/forum/#!topic/linux-sunxi/LOAxP3kAYs8
include/configs/sun4i.h | 4 ++-- include/configs/sun5i.h | 4 ++-- include/configs/sun7i.h | 4 ++-- include/configs/sunxi-common.h | 7 +++++++ 4 files changed, 13 insertions(+), 6 deletions(-)
diff --git a/include/configs/sun4i.h b/include/configs/sun4i.h index 87d269b..1537e53 100644 --- a/include/configs/sun4i.h +++ b/include/configs/sun4i.h @@ -13,8 +13,6 @@ */ #define CONFIG_CLK_FULL_SPEED 1008000000
-#define CONFIG_MACH_TYPE 4104 - #ifdef CONFIG_USB_EHCI #define CONFIG_USB_EHCI_SUNXI #define CONFIG_USB_MAX_CONTROLLER_COUNT 2 @@ -25,4 +23,6 @@ */ #include <configs/sunxi-common.h>
+#define CONFIG_MACH_TYPE (4104 | ((CONFIG_MACH_TYPE_COMPAT_REV) << 28)) + #endif /* __CONFIG_H */ diff --git a/include/configs/sun5i.h b/include/configs/sun5i.h index 52e3a6f..e755531 100644 --- a/include/configs/sun5i.h +++ b/include/configs/sun5i.h @@ -13,8 +13,6 @@ */ #define CONFIG_CLK_FULL_SPEED 1008000000
-#define CONFIG_MACH_TYPE 4138 - #ifdef CONFIG_USB_EHCI #define CONFIG_USB_EHCI_SUNXI #define CONFIG_USB_MAX_CONTROLLER_COUNT 1 @@ -25,4 +23,6 @@ */ #include <configs/sunxi-common.h>
+#define CONFIG_MACH_TYPE (4138 | ((CONFIG_MACH_TYPE_COMPAT_REV) << 28)) + #endif /* __CONFIG_H */ diff --git a/include/configs/sun7i.h b/include/configs/sun7i.h index 7cd7890..f817f73 100644 --- a/include/configs/sun7i.h +++ b/include/configs/sun7i.h @@ -14,8 +14,6 @@ */ #define CONFIG_CLK_FULL_SPEED 912000000
-#define CONFIG_MACH_TYPE 4283 - #ifdef CONFIG_USB_EHCI #define CONFIG_USB_EHCI_SUNXI #define CONFIG_USB_MAX_CONTROLLER_COUNT 2 @@ -31,4 +29,6 @@ */ #include <configs/sunxi-common.h>
+#define CONFIG_MACH_TYPE (4283 | ((CONFIG_MACH_TYPE_COMPAT_REV) << 28)) + #endif /* __CONFIG_H */ diff --git a/include/configs/sunxi-common.h b/include/configs/sunxi-common.h index 5ece020..f3e764a 100644 --- a/include/configs/sunxi-common.h +++ b/include/configs/sunxi-common.h @@ -14,6 +14,13 @@ #define _SUNXI_COMMON_CONFIG_H
/* + * Compatibility guard to prevent loading old buggy sunxi-3.4 kernels. + * Only sunxi-3.4 kernels with appropriate fixes applied are able to + * pass beyond the machine id check. + */ +#define CONFIG_MACH_TYPE_COMPAT_REV 1 + +/* * High Level Configuration Options */ #define CONFIG_SUNXI /* sunxi family */