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Date: Mon, 10 May 2021 20:58:37 +0200
From: Markus Wichmann <>
Subject: Re: Backwards kernel compatibility

On Mon, May 10, 2021 at 07:50:44AM +0200, Martin Vajnar wrote:
> Hello guys,
> I'd like to ask, if it is generally supported to run recent musl on older
> kernels? My primary concern is that there are new syscalls being added to
> linux, while at the same time I do not see a switch similar to glibc's to
> select compatibility mode (--enable-kernel). Is there some means which
> prevent invocation of unimplemented syscalls on older kernels when using
> musl?
> Best regards,
> Martin Vajnar

In general, musl tries to support all kernel versions from 2.6.0 on. If
you call a newer system call on a kernel that doesn't support it, you
will get ENOSYS back, but all algorithms implemented in the library will
fall back to that smallest common denominator (and some things even

There is no way to prevent calls to new system calls on older kernels,
since the kernel already takes care of that.


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