As the name suggests, syscalls are system calls, and they’re the way that you can make requests from user space into the Linux kernel. The kernel does some work for you, like creating a process, then hands control back to user space.
What is SYSCALL instruction in Linux kernel?
An application must fill general purpose registers with the correct values in the correct order and use the syscall instruction to make the actual system call. In this part we will look at what occurs in the Linux kernel when the syscall instruction is met by the processor.
Each call within the libc library is generally a syscall. X() macro, where X is the number of parameters used by the actual routine. Some system calls are more complex then others because of variable length argument lists, but even these complex system calls must use the same entry point: they just have more parameter setup overhead.
How does syscall call the system call handler?
As we can read in the Intel manual – 64-ia-32-architectures-software-developer-vol-2b-manual: SYSCALL invokes an OS system-call handler at privilege level 0. It does so by loading RIP from the IA32_LSTAR MSR it means that we need to put the system call entry in to the IA32_LSTAR model specific register.
But the Linux kernel does not call a sys_syscall_name function immediately after it is instructed to handle a system call from a user space application. Remember the chapter about interrupts and interrupt handling.
What is a Linux distro?
Linux isn’t like Windows or Mac OS X. Microsoft combines all the bits of Windows internally to produce each new release of Windows and distributes it as a single package. If you want Windows, you’ll need to choose one of the versions Microsoft is offering.
What linux distro command?
So in this post we are listing out some common commands that are used to detect distro specific information on linux. This includes the distro name and version. Lsb_release The lsb_release command prints out distribution specific information about a linux distro. On Ubuntu/debian based systems the command is available by default.
Is there a portable command for checking distro info across Linux systems?
Instead it reports the base distro name EL (Redhat). The following is an attempt to get a portable command for checking distro info across different linux systems. If one option fails, the command moves to the next one, until one of them works.
I and there is no single command that can detect distribution specific information consistently across all linux distributions. The command is different across Debian, Cent. OS and Arch, and linux. So in this post we are listing out some common commands that are used to detect distro specific information on linux.
How to check distro name and version in Linux?
, and lsb_release. The lsb_release command prints out distribution specific information about a linux distro., and /etc/*-release files., and cat /proc/version., and uname -a.