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| author | Michael Brown | 2015-03-04 19:48:19 +0100 |
|---|---|---|
| committer | Michael Brown | 2015-03-05 01:59:38 +0100 |
| commit | fbc4ba4b4ed13cc86cb8fdea0bac6c3be0164ed5 (patch) | |
| tree | a0c504e297806aa88e89a04e694333a7c5172757 /src/arch/x86 | |
| parent | [build] Use REQUIRE_OBJECT() to drag in per-object configuration (diff) | |
| download | ipxe-fbc4ba4b4ed13cc86cb8fdea0bac6c3be0164ed5.tar.gz ipxe-fbc4ba4b4ed13cc86cb8fdea0bac6c3be0164ed5.tar.xz ipxe-fbc4ba4b4ed13cc86cb8fdea0bac6c3be0164ed5.zip | |
[build] Fix the REQUIRE_SYMBOL mechanism
At some point in the past few years, binutils became more aggressive
at removing unused symbols. To function as a symbol requirement, a
relocation record must now be in a section marked with @progbits and
must not be in a section which gets discarded during the link (either
via --gc-sections or via /DISCARD/).
Update REQUIRE_SYMBOL() to generate relocation records meeting these
criteria. To minimise the impact upon the final binary size, we use
existing symbols (specified via the REQUIRING_SYMBOL() macro) as the
relocation targets where possible. We use R_386_NONE or R_X86_64_NONE
relocation types to prevent any actual unwanted relocation taking
place. Where no suitable symbol exists for REQUIRING_SYMBOL() (such
as in config.c), the macro PROVIDE_REQUIRING_SYMBOL() can be used to
generate a one-byte-long symbol to act as the relocation target.
If there are versions of binutils for which this approach fails, then
the fallback will probably involve killing off REQUEST_SYMBOL(),
redefining REQUIRE_SYMBOL() to use the current definition of
REQUEST_SYMBOL(), and postprocessing the linked ELF file with
something along the lines of "nm -u | wc -l" to check that there are
no undefined symbols remaining.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Diffstat (limited to 'src/arch/x86')
| -rw-r--r-- | src/arch/x86/drivers/hyperv/hyperv.c | 3 | ||||
| -rw-r--r-- | src/arch/x86/drivers/xen/hvm.c | 3 |
2 files changed, 6 insertions, 0 deletions
diff --git a/src/arch/x86/drivers/hyperv/hyperv.c b/src/arch/x86/drivers/hyperv/hyperv.c index c3c0e86c0..f73829bd5 100644 --- a/src/arch/x86/drivers/hyperv/hyperv.c +++ b/src/arch/x86/drivers/hyperv/hyperv.c @@ -590,5 +590,8 @@ struct root_device hv_root_device __root_device = { .driver = &hv_root_driver, }; +/* Drag in objects via hv_root_device */ +REQUIRING_SYMBOL ( hv_root_device ); + /* Drag in netvsc driver */ REQUIRE_OBJECT ( netvsc ); diff --git a/src/arch/x86/drivers/xen/hvm.c b/src/arch/x86/drivers/xen/hvm.c index 6f3be8e2e..7ac32d54c 100644 --- a/src/arch/x86/drivers/xen/hvm.c +++ b/src/arch/x86/drivers/xen/hvm.c @@ -496,5 +496,8 @@ struct pci_driver hvm_driver __pci_driver = { .remove = hvm_remove, }; +/* Drag in objects via hvm_driver */ +REQUIRING_SYMBOL ( hvm_driver ); + /* Drag in netfront driver */ REQUIRE_OBJECT ( netfront ); |