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SubjectRe: [PATCH 1/3] microblaze: Replace NR_syscalls macro from asm/unistd.h
On 9 August 2018 at 12:18, Michal Simek <> 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 <>
> AuthorDate: Mon Jul 8 09:50:24 2013 +0200
> Commit: Michal Simek <>
> 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

- Firoz

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