Fix switchless sample code

[xu-cheng]

In order to use the switchless feature of the SGX, the app binary needs
to be linked with the following flags.

-Wl,--whole-archive -lsgx_uswitchless -Wl,--no-whole-archive

Noted that there is currently no proper way to pass custom link flags to
all the binaries in a cargo project. As such, the link_args macro need
to be set for each of Rust files with main methods.

References:

• Build flags used in Intel SGX sample code: https://github.com/intel/linux-sgx/blob/ce4a18d9a0963b14f717cc7462241cfadd233f55/SampleCode/Switchless/Makefile#L104
• Rust tracking issue on link_args: Tracking issue for link_args stabilization rust-lang/rust#29596
• PR for cargo:rustc-link-arg-bins in cargo build script: Finish implementation of -Zextra-link-arg. rust-lang/cargo#8441

[dingelish]

thanks!

[rashmik8]

I understand this issue has been closed but I needed more clarity on this one. I tried including -Wl,--whole-archive -lsgx_uswitchless -Wl,--no-whole-archive in my file with main() however I run into following error:
= note: /opt/intel/sgxsdk/lib64/libsgx_uswitchless.a(sl_urts_loader_untrusted.o): In function urts_loader_t::urts_loader_t()':
sl_urts_loader_untrusted.cpp:(.text._ZN13urts_loader_tC2Ev+0x8): undefined reference to sgx_set_switchless_itf' /opt/intel/sgxsdk/lib64/libsgx_uswitchless.a(sl_workers_untrusted.o): In function tworker_process_calls':
sl_workers_untrusted.c:(.text.tworker_process_calls+0x21): undefined reference to sl_run_switchless_tworker' /opt/intel/sgxsdk/lib64/libsgx_uswitchless.a(sgx_ecall_switchless_untrusted.o): In function init_tswitchless':
sgx_ecall_switchless_untrusted.c:(.text.init_tswitchless+0x10): undefined reference to sl_init_switchless' collect2: error: ld returned 1 exit status
Looks like it cannot find sgx_urts or other files. Not sure what I am missing here.
Apologies in advance if this is not the right place to post this.

[volcano0dr]

I understand this issue has been closed but I needed more clarity on this one. I tried including -Wl,--whole-archive -lsgx_uswitchless -Wl,--no-whole-archive in my file with main() however I run into following error: = note: /opt/intel/sgxsdk/lib64/libsgx_uswitchless.a(sl_urts_loader_untrusted.o): In function urts_loader_t::urts_loader_t()': sl_urts_loader_untrusted.cpp:(.text._ZN13urts_loader_tC2Ev+0x8): undefined reference to sgx_set_switchless_itf' /opt/intel/sgxsdk/lib64/libsgx_uswitchless.a(sl_workers_untrusted.o): In function tworker_process_calls': sl_workers_untrusted.c:(.text.tworker_process_calls+0x21): undefined reference to sl_run_switchless_tworker' /opt/intel/sgxsdk/lib64/libsgx_uswitchless.a(sgx_ecall_switchless_untrusted.o): In function init_tswitchless': sgx_ecall_switchless_untrusted.c:(.text.init_tswitchless+0x10): undefined reference to sl_init_switchless' collect2: error: ld returned 1 exit status Looks like it cannot find sgx_urts or other files. Not sure what I am missing here. Apologies in advance if this is not the right place to post this.

You can refer to switchless example

[rashmik8]

Hi @volcano0dr , thank you for your response. I did refer to this switchless example. However, it still doesn't work.
Original post states that the switchless flag is required in link_args wherever main is. Does this mean entry point? My cargo project builds internally calls to build shared library with trusted and untrusted code. The error I run into is linking of this sgx_uswitchless, where the error probably wants path using -L. But that causes a cascaded effect as it cannot find other dependent libraries. Also does it necessary have to be main.rs? Currently I have it included in my lib.rs file of project, but I still receive SGX_ERROR_UNEXPECTED. Mimicked the build steps of switchless code example but to no avail.