Robert Millan wrote:
On Wed, Nov 05, 2008 at 10:41:20PM +0100, Christian Franke wrote:
Then, a module author has the option to check the ABI version by
importing this symbol
(possibly by simply adding '-u grub_abi_VERSION' to ld command)
How would the whole picture look like? Sounds like it'd mean less complexity
in external modules at the expense of more complexity in the build system.
Here a first proof-of-concept patch, uses hello.c as the external module.
If kernel is compiled with other GRUB_ABI_VER_SYM, insmod fails with:
"error: the symbol 'grub_abi_ver_1_96' not found"
Christian
diff --git a/hello/hello.c b/hello/hello.c
index 70cbf60..4eb2483 100644
--- a/hello/hello.c
+++ b/hello/hello.c
@@ -25,6 +25,8 @@
#include <grub/dl.h>
#include <grub/normal.h>
+GRUB_ABI_VER_CHECK;
+
static grub_err_t
grub_cmd_hello (struct grub_arg_list *state __attribute__ ((unused)),
int argc __attribute__ ((unused)),
diff --git a/include/grub/dl.h b/include/grub/dl.h
index bdde089..3efc05e 100644
--- a/include/grub/dl.h
+++ b/include/grub/dl.h
@@ -93,4 +93,11 @@ void *EXPORT_FUNC(grub_dl_resolve_symbol) (const char *name);
grub_err_t grub_arch_dl_check_header (void *ehdr);
grub_err_t grub_arch_dl_relocate_symbols (grub_dl_t mod, void *ehdr);
+#define GRUB_ABI_VER_SYM grub_abi_ver_1_96
+
+extern char EXPORT_VAR(GRUB_ABI_VER_SYM);
+
+#define GRUB_ABI_VER_CHECK \
+char * grub_abi_ver_check = &GRUB_ABI_VER_SYM
+
#endif /* ! GRUB_DL_H */
diff --git a/kern/dl.c b/kern/dl.c
index b483134..32591f4 100644
--- a/kern/dl.c
+++ b/kern/dl.c
@@ -29,6 +29,8 @@
#include <grub/env.h>
#include <grub/cache.h>
+char GRUB_ABI_VER_SYM;
+
#if GRUB_CPU_SIZEOF_VOID_P == 4
typedef Elf32_Word Elf_Word;
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