Sender: Emil Renner Berthing <emil.renner.berthing@gmail.com>
From:   Emil Renner Berthing <kernel@esmil.dk>
To:     Ley Foon Tan <lftan.linux@gmail.com>,
        Matteo Croce <mcroce@linux.microsoft.com>
Cc:     Emil Renner Berthing <kernel@esmil.dk>,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-arch@vger.kernel.org,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Akira Tsukamoto <akira.tsukamoto@gmail.com>,
        Drew Fustini <drew@beagleboard.org>,
        Bin Meng <bmeng.cn@gmail.com>,
        David Laight <David.Laight@aculab.com>,
        Guo Ren <guoren@kernel.org>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v5 3/3] riscv: optimized memset
Date:   Mon,  6 Dec 2021 21:37:03 +0100
Message-Id: <20211206203703.67597-1-kernel@esmil.dk>
In-Reply-To: <CAFiDJ5-OJzWWR0hSZDsuAmxzxTE7cRR9Bsetpfh5vvrTxzkKPw@mail.gmail.com>
References: <CAFiDJ5-OJzWWR0hSZDsuAmxzxTE7cRR9Bsetpfh5vvrTxzkKPw@mail.gmail.com>
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Hi Ley Foon,

You're right it doesn't boot for me either when building with

  make ARCH=riscv LLVM=1

The following patch fixes it for me though. In hindsigt it's perhaps a
bit surprising it works without -ffreestanding in GCC.

/Emil

---
 arch/riscv/lib/Makefile | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile
index e33263cc622a..6dfa919d4cd6 100644
--- a/arch/riscv/lib/Makefile
+++ b/arch/riscv/lib/Makefile
@@ -4,4 +4,9 @@ lib-$(CONFIG_MMU)	+= uaccess.o
 lib-$(CONFIG_64BIT)	+= tishift.o
 lib-$(CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE) += string.o
 
+# string.o implements standard library functions like memset/memcpy etc.
+# Use -ffreestanding to ensure that the compiler does not try to "optimize"
+# them into calls to themselves.
+CFLAGS_string.o := -ffreestanding
+
 obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o
-- 
2.34.1