Re: [PATCH] binfmt_misc: pass binfmt_misc P flag to the interpreter

From: YunQiang Su
Date: Fri Mar 06 2020 - 06:48:49 EST


Florian Weimer <fw@xxxxxxxxxxxxx> ä2020å3æ6æåä äå7:42åéï
>
> * 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.