Le 06/03/2020 à 12:48, YunQiang Su a écrit : > Florian Weimer <fw@xxxxxxxxxxxxx> 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
