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From: Laurent Vivier <laurent@vivier.eu>
To: YunQiang Su <syq@debian.org>, Florian Weimer <fw@deneb.enyo.de>
Cc: torvalds@linux-foundation.org,
	Greg KH <gregkh@linuxfoundation.org>,
	akpm@linux-foundation.org, Al Viro <viro@zeniv.linux.org.uk>,
	James Bottomley <James.Bottomley@hansenpartnership.com>,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-arch@vger.kernel.org, linux-api@vger.kernel.org,
	libc-alpha@sourceware.org
Subject: Re: [PATCH] binfmt_misc: pass binfmt_misc P flag to the interpreter
Date: Fri, 6 Mar 2020 13:07:35 +0100	[thread overview]
Message-ID: <fded1845-98db-f0fb-9320-842c9fdc30dc@vivier.eu> (raw)
In-Reply-To: <CAKcpw6VF1N2gTVXeWLU4aVOuARf5oN6yPg9O=RCzgkMrjXmxYQ@mail.gmail.com>

Le 06/03/2020 à 12:48, YunQiang Su a écrit :
> Florian Weimer <fw@deneb.enyo.de> 于2020年3月6日周五 下午7:42写道:
>>
>> * YunQiang Su:
>>
>>> AT_* only has 32 slot and now. I was afraid that maybe we shouldn't take one.
>>>    /* AT_* values 18 through 22 are reserved */
>>>    27,28,29,30 are not used now.
>>> Which should we use?
>>
>> Where does this limit of 32 tags come from?  I don't see it from a
>> userspace perspective.
> 
> Sorry it is my mistake: In linux/auxvec.h, I saw
> 
> #define AT_RANDOM 25    /* address of 16 random bytes */
> #define AT_HWCAP2 26    /* extension of AT_HWCAP */
> 
> #define AT_EXECFN  31   /* filename of program */
> 
> The number jump to 31 from 26.
> 
> It is my fault: in x86_64-linux-gnu/bits/auxv.h, the max number is 47 now.
> 

Numbers starting from 32 are arch specific.
18 to 22 are also reserved (and used by some archs).
(linux/arch/*/include/uapi/asm/auxvec.h)

So there is only 4 entries available (27 to 30)
(linux/include/uapi/linux/auxvec.h)
Do we want to waste one more entry whereas we can use an unused one?

Thanks,
Laurent

  parent reply	other threads:[~2020-03-06 12:07 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-06  8:09 [PATCH] binfmt_misc: pass binfmt_misc P flag to the interpreter YunQiang Su
2020-03-06  8:13 ` Florian Weimer
2020-03-06  8:21   ` Laurent Vivier
2020-03-06  8:37     ` Florian Weimer
2020-03-06 11:13       ` Laurent Vivier
2020-03-06 11:29         ` YunQiang Su
2020-03-06 11:40           ` Florian Weimer
2020-03-06 11:48             ` YunQiang Su
2020-03-06 12:07               ` Florian Weimer
2020-03-06 12:07               ` Laurent Vivier [this message]
2020-03-11  9:09 ` Laurent Vivier

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