On 06.12.25 00:28, Jason Andryuk wrote:
When linking to create xen-syms, add --gc-sections to garbage collect
unused stuff. Relies on CONFIG_CC_SPLIT_SECTIONS
We need to add KEEP() to the linker script in assorted places to retain
appropriate data - especially the arrays created therein.
Something is off though. In a test where memory_add() is unreachable,
it is still included. I'm not sure, but I am wondering if it's the
alternatives somehow keeping a reference to it.
Signed-off-by: Jason Andryuk <[email protected]>
---
With --print-gc-sections on defconfig:
ld: removing unused section '.text.__bitmap_full' in file 'prelink.o'
ld: removing unused section '.text.__bitmap_xor' in file 'prelink.o'
ld: removing unused section '.text.__bitmap_set' in file 'prelink.o'
ld: removing unused section '.text.__bitmap_clear' in file 'prelink.o'
ld: removing unused section '.text.bitmap_find_free_region' in file 'prelink.o'
ld: removing unused section '.text.bitmap_release_region' in file 'prelink.o'
ld: removing unused section '.text.domain_has_ioreq_server' in file 'prelink.o'
ld: removing unused section '.text.compat_kexec_op' in file 'prelink.o'
ld: removing unused section '.text.in_atomic' in file 'prelink.o'
ld: removing unused section '.text.radix_tree_next_hole' in file 'prelink.o'
ld: removing unused section '.text.radix_tree_prev_hole' in file 'prelink.o'
ld: removing unused section '.text.radix_tree_gang_lookup_slot' in file
'prelink.o'
ld: removing unused section '.text._nrspin_trylock' in file 'prelink.o'
ld: removing unused section '.text.xen_compile_host' in file 'prelink.o'
ld: removing unused section '.text.vscnprintf' in file 'prelink.o'
ld: removing unused section '.text.wake_up_one' in file 'prelink.o'
ld: removing unused section '.text.xmem_pool_get_used_size' in file 'prelink.o'
ld: removing unused section '.text.xmem_pool_get_total_size' in file 'prelink.o'
ld: removing unused section '.text.xmem_pool_maxalloc' in file 'prelink.o'
ld: removing unused section '.text.xlat_start_info' in file 'prelink.o'
ld: removing unused section '.text.elf_sym_by_name' in file 'prelink.o'
ld: removing unused section '.text.elf_sym_by_index' in file 'prelink.o'
ld: removing unused section '.text.elf_get_ptr' in file 'prelink.o'
ld: removing unused section '.text.elf_lookup_addr' in file 'prelink.o'
ld: removing unused section '.text.serial_vuart_info' in file 'prelink.o'
ld: removing unused section '.text.pci_find_next_cap' in file 'prelink.o'
ld: removing unused section '.text.free_hvm_irq_dpci' in file 'prelink.o'
ld: removing unused section '.text.mce_barrier_init' in file 'prelink.o'
ld: removing unused section '.text.mce_barrier_dec' in file 'prelink.o'
ld: removing unused section '.text.mce_barrier' in file 'prelink.o'
ld: removing unused section '.text.apei_read_mce' in file 'prelink.o'
ld: removing unused section '.text.apei_check_mce' in file 'prelink.o'
ld: removing unused section '.text.apei_clear_mce' in file 'prelink.o'
ld: removing unused section '.text.efi_halt_system' in file 'prelink.o'
ld: removing unused section '.text.get_vvmcs_virtual_safe' in file 'prelink.o'
ld: removing unused section '.text.get_vvmcs_real_safe' in file 'prelink.o'
ld: removing unused section '.text.set_vvmcs_real' in file 'prelink.o'
ld: removing unused section '.text.set_vvmcs_virtual_safe' in file 'prelink.o'
ld: removing unused section '.text.set_vvmcs_real_safe' in file 'prelink.o'
ld: removing unused section '.text.domain_set_alloc_bitsize' in file 'prelink.o'
ld: removing unused section '.text.watchdog_enabled' in file 'prelink.o'
ld: removing unused section '.text.unset_nmi_callback' in file 'prelink.o'
ld: removing unused section '.text.sha2_256_init' in file 'prelink.o'
ld: removing unused section '.text.xxh64_copy_state' in file 'prelink.o'
ld: removing unused section '.text.xxh64' in file 'prelink.o'
ld: removing unused section '.discard' in file 'prelink.o'
ld: removing unused section '.rodata.xen_compile_host.str1.1' in file
'prelink.o'
ld: removing unused section '.rodata.elf_lookup_addr.str1.1' in file 'prelink.o'
ld: removing unused section '.rodata.apei_read_mce.str1.8' in file 'prelink.o'
ld: removing unused section '.rodata.efi_halt_system.str1.8' in file 'prelink.o'
ld: removing unused section '.rodata.play_dead.str1.1' in file 'prelink.o'
ld: removing unused section '.data.rel.ro.local.fetch_type_names' in file
'prelink.o'
---
xen/arch/x86/Makefile | 3 +++
xen/arch/x86/xen.lds.S | 38 +++++++++++++++++++-------------------
xen/include/xen/xen.lds.h | 18 +++++++++---------
3 files changed, 31 insertions(+), 28 deletions(-)
diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index 300cc67407..934c79411a 100644
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -137,18 +137,21 @@ $(TARGET)-syms: $(objtree)/prelink.o $(obj)/xen.lds
$(objtree)/tools/symbols $(all_symbols) --empty > $(dot-target).0.S
$(MAKE) $(build)=$(@D) $(dot-target).0.o
$(LD) $(XEN_LDFLAGS) -T $(obj)/xen.lds $< $(build_id_linker) \
+ --gc-sections \
$(dot-target).0.o -o $(dot-target).0
$(NM) -pa --format=sysv $(dot-target).0 \
| $(objtree)/tools/symbols $(all_symbols) --sysv --sort \
> $(dot-target).1.S
$(MAKE) $(build)=$(@D) $(dot-target).1.o
$(LD) $(XEN_LDFLAGS) -T $(obj)/xen.lds $< $(build_id_linker) \
+ --gc-sections \
$(dot-target).1.o -o $(dot-target).1
$(NM) -pa --format=sysv $(dot-target).1 \
| $(objtree)/tools/symbols $(all_symbols) --sysv --sort
$(syms-warn-dup-y) \
> $(dot-target).2.S
$(MAKE) $(build)=$(@D) $(dot-target).2.o
$(LD) $(XEN_LDFLAGS) -T $(obj)/xen.lds $< $(build_id_linker) \
+ --gc-sections \
It should work if --gc-sections is used only here - last LD statement.
$(orphan-handling-y) $(dot-target).2.o -o $@
$(NM) -pa --format=sysv $@ \
| $(objtree)/tools/symbols --all-symbols --xensyms --sysv
--sort \
--
Best regards,
-grygorii
