linux-kernel - Re: [PATCH 5/5] selftests/sgx: Enclave freestanding compilation + separate linker options.

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Date:   Mon, 7 Aug 2023 12:03:58 +0200
From:   Jo Van Bulck <jo.vanbulck@...kuleuven.be>
To:     Jarkko Sakkinen <jarkko@...nel.org>, linux-sgx@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     dave.hansen@...ux.intel.com
Subject: Re: [PATCH 5/5] selftests/sgx: Enclave freestanding compilation +
 separate linker options.

On 28.07.23 21:22, Jarkko Sakkinen wrote:
> Should be split into two patches. 

Thanks, will do in the next patch revision.

> Please describe the motivation for the
> second paragraph in the patch, which adds '-ffreestanding'.

Even when passing -nostdlib, the compiler still assumes memset and 
memcpy are present [1].

I found that, when not passing '-ffreestanding', clang seems to optimize 
away the existing memcpy/memset implementations and errors with:

/bin/ld: test_encl.o: in function `do_encl_init_tcs_page':
test_encl.c:(.text+0x17e): undefined reference to `memset'

I will add this information in the next patch revision.

[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90701

Best,
Jo