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Diffstat (limited to 'Documentation/kbuild/makefiles.txt')
| -rw-r--r-- | Documentation/kbuild/makefiles.txt | 28 |
1 files changed, 14 insertions, 14 deletions
diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt index 71e9feefb63c..048fc39a6b91 100644 --- a/Documentation/kbuild/makefiles.txt +++ b/Documentation/kbuild/makefiles.txt @@ -153,12 +153,18 @@ more details, with real examples. configuration. Kbuild compiles all the $(obj-y) files. It then calls - "$(LD) -r" to merge these files into one built-in.o file. - built-in.o is later linked into vmlinux by the parent Makefile. + "$(AR) rcSTP" to merge these files into one built-in.a file. + This is a thin archive without a symbol table, which makes it + unsuitable as a linker input. + + The scripts/link-vmlinux.sh script later makes an aggregate + built-in.a with "${AR} rcsTP", which creates the thin archive + with a symbol table and an index, making it a valid input for + the final vmlinux link passes. The order of files in $(obj-y) is significant. Duplicates in the lists are allowed: the first instance will be linked into - built-in.o and succeeding instances will be ignored. + built-in.a and succeeding instances will be ignored. Link order is significant, because certain functions (module_init() / __initcall) will be called during boot in the @@ -222,7 +228,7 @@ more details, with real examples. Note: Of course, when you are building objects into the kernel, the syntax above will also work. So, if you have CONFIG_EXT2_FS=y, kbuild will build an ext2.o file for you out of the individual - parts and then link this into built-in.o, as you would expect. + parts and then link this into built-in.a, as you would expect. --- 3.4 Objects which export symbols @@ -232,7 +238,7 @@ more details, with real examples. --- 3.5 Library file goals - lib-y Objects listed with obj-* are used for modules, or - combined in a built-in.o for that specific directory. + combined in a built-in.a for that specific directory. There is also the possibility to list objects that will be included in a library, lib.a. All objects listed with lib-y are combined in a single @@ -244,7 +250,7 @@ more details, with real examples. Note that the same kbuild makefile may list files to be built-in and to be part of a library. Therefore the same directory - may contain both a built-in.o and a lib.a file. + may contain both a built-in.a and a lib.a file. Example: #arch/x86/lib/Makefile @@ -831,12 +837,6 @@ When kbuild executes, the following steps are followed (roughly): Note: ldflags-y can be used to further customise the flags used. See chapter 3.7. - LDFLAGS_MODULE Options for $(LD) when linking modules - - LDFLAGS_MODULE is used to set specific flags for $(LD) when - linking the .ko files used for modules. - Default is "-r", for relocatable output. - LDFLAGS_vmlinux Options for $(LD) when linking vmlinux LDFLAGS_vmlinux is used to specify additional flags to pass to @@ -986,7 +986,7 @@ When kbuild executes, the following steps are followed (roughly): $(head-y) lists objects to be linked first in vmlinux. $(libs-y) lists directories where a lib.a archive can be located. - The rest list directories where a built-in.o object file can be + The rest list directories where a built-in.a object file can be located. $(init-y) objects will be located after $(head-y). @@ -1071,7 +1071,7 @@ When kbuild executes, the following steps are followed (roughly): extra-y := head.o init_task.o In this example, extra-y is used to list object files that - shall be built, but shall not be linked as part of built-in.o. + shall be built, but shall not be linked as part of built-in.a. --- 6.7 Commands useful for building a boot image |