On 9 August 2018 at 12:18, Michal Simek <michal.simek@xxxxxxxxxx> wrote: > On 9.8.2018 07:27, Firoz Khan wrote: >> __NR_syscalls macro holds the number of system call exist in this >> architecture. This macro is currently the part of asm/unistd.h file. >> We have change the value of __NR_syscalls, if we add or delete a >> system call. >> >> One of the patch in this patch series has a script which will >> generate a uapi header based on syscall.tbl file. The syscall.tbl >> file contains the number of system call information. So we have >> two option to update __NR_syscalls value. >> >> 1. Update __NR_syscalls in asm/unistd.h manually by counting the >> no.of system calls. No need to update __NR_syscalls untill >> we either add a new system call or delete an existing system >> call. >> >> 2. We can keep this feature it above mentioned script, that'll >> count the number of syscalls and keep it in a generated file. >> In this case we don't need to explicitly update __NR_syscalls >> in asm/unistd.h file. >> >> The 2nd option will be the recommended one. For that, I moved the >> NR_syscalls macro from asm/unistd.h to uapi/asm/unistd.h. The macro >> name also changed form NR_syscalls to __NR_syscalls for making the >> name convention same across all architecture. While __NR_syscalls >> isn't strictly part of the uapi, having it as part of the generated >> header to simplifies the implementation. > > This macro was in unistd.h in past but it was moved out because it was > causing problem with strace. > > commit 40c2702a02b755e0183b702778331b351f3be20c > Author: Michal Simek <michal.simek@xxxxxxxxxx> > AuthorDate: Mon Jul 8 09:50:24 2013 +0200 > Commit: Michal Simek <michal.simek@xxxxxxxxxx> > CommitDate: Wed Jul 10 07:32:09 2013 +0200 > > microblaze: Move __NR_syscalls from uapi > > > That's why I don't think this is the right thing to do. > I have grepped strace and glibc and none is using this macro that's why > I think it shouldn't be exported via uapi. Thanks for you reply :) Sorry for the delayed response :( I would like to keep __NR_syscalls macro to uapi header in order to simplify the system call table generation script. Otherwise the __NR_syscalls macro need to update manually. That become a problem. Please check the below implementation in uapi file make sense? It is an easy workaround to leave __NR_syscalls macro in uapi/asm/unistd.h and enclose it in #ifdef __KERNEL__ ... ... #define __NR_pkey_free 397 #define __NR_statx 398 #ifdef __KERNEL__ #define __NR_syscalls 399 #endif ... ... - Firoz
