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From: Thomas Gleixner <tglx@linutronix.de>
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To: K Prateek Nayak <kprateek.nayak@amd.com>, LKML
 <linux-kernel@vger.kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>, linux-arch@vger.kernel.org, Peter Zilstra
 <peterz@infradead.org>, Mathieu Desnoyers
 <mathieu.desnoyers@efficios.com>, "Paul E. McKenney" <paulmck@kernel.org>,
 Boqun Feng <boqun.feng@gmail.com>, Jonathan Corbet <corbet@lwn.net>,
 Prakash Sangappa <prakash.sangappa@oracle.com>, Madadi Vineeth Reddy
 <vineethr@linux.ibm.com>, Steven Rostedt <rostedt@goodmis.org>, Sebastian
 Andrzej Siewior <bigeasy@linutronix.de>
Subject: Re: [patch 06/12] rseq: Implement sys_rseq_slice_yield()
In-Reply-To: <47499513-7bf0-4393-ba89-5efd9c115c43@amd.com>
References: <20250908225709.144709889@linutronix.de>
 <20250908225752.936257349@linutronix.de>
 <47499513-7bf0-4393-ba89-5efd9c115c43@amd.com>
Date: Tue, 09 Sep 2025 14:23:38 +0200
Message-ID: <87plbzvmph.ffs@tglx>
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On Tue, Sep 09 2025 at 15:22, K. Prateek Nayak wrote:
> On 9/9/2025 4:30 AM, Thomas Gleixner wrote:
>>  /* restartable sequence */
>>  COND_SYSCALL(rseq);
>> +COND_SYSCALL(rseq_sched_yield);
>
> I'm not sure if it is my toolchain but when I try to build a version
> with CONFIG_RSEQ_SLICE_EXTENSION disabled, I see:
>
>     ld: vmlinux.o: in function `x64_sys_call':
>     arch/x86/include/generated/asm/syscalls_64.h:471: undefined reference to `__x64_sys_rseq_slice_yield'
>     ld: vmlinux.o: in function `ia32_sys_call':
>     arch/x86/include/generated/asm/syscalls_32.h:471: undefined reference to `__ia32_sys_rseq_slice_yield'
>     ld: vmlinux.o:(.rodata+0x12d0): undefined reference to `__x64_sys_rseq_slice_yield'
>
> I would have assumed the COND_SYSCALL() above would have stubbed this
> but that doesn't seem to be the case. Am I missing something?

Yes.

>> +COND_SYSCALL(rseq_sched_yield);

does not create a stub for rseq_slice_yield() obviously :)

/me looks for a brown paperbag.