linux-kernel - Re: [PATCH] sh: remove CONFIG

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Message-ID: <9dfb01dced05b0efe0dbde22b8470e0b0bbc5b38.camel@physik.fu-berlin.de>
Date: Mon, 12 Jan 2026 13:01:06 +0100
From: John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
To: Thomas Weißschuh <thomas.weissschuh@...utronix.de>
Cc: Yoshinori Sato <ysato@...rs.sourceforge.jp>, Rich Felker
 <dalias@...c.org>,  Arnd Bergmann	 <arnd@...db.de>,
 linux-sh@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sh: remove CONFIG_VSYSCALL reference from UAPI

Hi,

On Mon, 2026-01-12 at 12:58 +0100, Thomas Weißschuh wrote:
> > Thanks for your patch!
> > 
> > I don't really know what AT_SYSINFO_EHDR is about. Could you explain the background
> > a little so that I have a better understanding of what I am reviewing?
> 
> It is the entrypoint to the vDSO. From getauxval(3):
> 
>  AT_SYSINFO_EHDR
>         The address of a page containing the virtual Dynamic Shared Object (vDSO) that the kernel creates
>         in order to provide fast implementations of certain system calls.
> 
> 
> That UAPI constant needs to be exposed to userspace even if the specific
> kernel does not have a vDSO. This is the current behavior which is preserved.
> Userspace will detect the presence or absence of the vDSO based in the
> auxiliary vector.

Thanks, this explains a lot. I will review the patch later this week.

Adrian

-- 
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