Re: [PATCH] tools/testing/cxl: Don't wrap cxl_core's own exported symbols

On Tue, Jul 21, 2026 at 04:40:09PM +0800, Richard Cheng wrote:
> Building cxl_test with LLVM=1 (ld.lld) fails in modpost:
> 
> """
>   cxl_core: .export_symbol section references '__wrap_...', but it
>   does not seem to be an export symbol
> """
> 
> cxl_test --wraps 6 symbols that cxl_core both defines and exports.
> GNU ld only wraps undefined references, but ld.lld also redirects
> references to defined symbols, so cxl_core's own EXPORT_SYMBOL entries
> get rewritten to __wrap_* and modpost rejects them.
> 
> cxl_core never calls these symbols, so wrap them only in the caller
> modules via LDFLAGS_<module>.o instead of the global ldflags-y.
> 
> Signed-off-by: Richard Cheng <[email protected]>
> ---
>  tools/testing/cxl/Kbuild | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/testing/cxl/Kbuild b/tools/testing/cxl/Kbuild
> index 2be1df80fcc9..e49ce644b4b1 100644
> --- a/tools/testing/cxl/Kbuild
> +++ b/tools/testing/cxl/Kbuild
> @@ -4,16 +4,20 @@ ldflags-y += --wrap=is_acpi_device_node
>  ldflags-y += --wrap=acpi_evaluate_integer
>  ldflags-y += --wrap=acpi_pci_find_root
>  ldflags-y += --wrap=nvdimm_bus_register
> -ldflags-y += --wrap=cxl_await_media_ready
> -ldflags-y += --wrap=devm_cxl_add_rch_dport
> -ldflags-y += --wrap=cxl_endpoint_parse_cdat
> -ldflags-y += --wrap=devm_cxl_endpoint_decoders_setup
>  ldflags-y += --wrap=hmat_get_extended_linear_cache_size
> -ldflags-y += --wrap=devm_cxl_add_dport_by_dev
> -ldflags-y += --wrap=devm_cxl_switch_port_decoders_setup
>  ldflags-y += --wrap=walk_hmem_resources
>  ldflags-y += --wrap=region_intersects
>  ldflags-y += --wrap=region_intersects_soft_reserve
> +wrap_cxl_core := --wrap=cxl_await_media_ready
> +wrap_cxl_core += --wrap=devm_cxl_add_rch_dport
> +wrap_cxl_core += --wrap=devm_cxl_add_dport_by_dev
> +wrap_cxl_core += --wrap=devm_cxl_switch_port_decoders_setup
> +wrap_cxl_core += --wrap=devm_cxl_endpoint_decoders_setup
> +wrap_cxl_core += --wrap=cxl_endpoint_parse_cdat
> +LDFLAGS_cxl_acpi.o += $(wrap_cxl_core)
> +LDFLAGS_cxl_pmem.o += $(wrap_cxl_core)
> +LDFLAGS_cxl_port.o += $(wrap_cxl_core)
> +LDFLAGS_cxl_mem.o  += $(wrap_cxl_core)
>  
>  DRIVERS := ../../../drivers
>  DAX_HMEM_SRC := $(DRIVERS)/dax/hmem
> -- 
> 2.43.0
>

Hi Richard,

I was hitting the same tools/testing/cxl build failure on current cxl/next.
modpost was failing on wrapped CXL symbols, for example:

.export_symbol section references '__wrap_devm_cxl_add_rch_dport',
but it does not seem to be an export symbol

.export_symbol section references '__wrap_devm_cxl_add_dport_by_dev',
but it does not seem to be an export symbol

.export_symbol section references '__wrap_cxl_await_media_ready',
but it does not seem to be an export symbol

I found this patch while investigating the failure and applied it to my tree. 
With the patch applied, the wrapped-symbol build issue is resolved and tools/testing/cxl 
builds successfully for me.

Tested-by: Shaikh Kamaluddin <[email protected]>