From 90f1c92fd3b04d4964772dc7a21fb3a4c1f9c534 Mon Sep 17 00:00:00 2001 From: Michael Kerrisk Date: Mon, 23 Nov 2020 07:26:10 +0100 Subject: [PATCH] lseek64.3: srcfix: add some comments to remind myself of some details Signed-off-by: Michael Kerrisk --- man3/lseek64.3 | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/man3/lseek64.3 b/man3/lseek64.3 index 9325203e1..732c39fa5 100644 --- a/man3/lseek64.3 +++ b/man3/lseek64.3 @@ -170,6 +170,18 @@ system call. Instead, they have an .BR lseek (2) system call that supports 64-bit file offsets. +.\" In arch/x86/entry/syscalls/syscall_32.tbl, +.\" we see the following line: +.\" +.\" 140 i386 _llseek sys_llseek +.\" +.\" This is essentially telling us that 'sys_llseek' (the name generated +.\" by SYSCALL_DEFINE5(llseek...)) is exposed to user-space as system call +.\" number 140, and that system call number will (IIUC) be exposed in +.\" autogenerated headers with the name "__NR__llseek" (i.e., "_llseek"). +.\" The "i386" is telling us that this happens in i386 (32-bit Intel). +.\" There is nothing equivalent on x86-64, because 64 bit systems don't +.\" need an _llseek system call. .SH ATTRIBUTES For an explanation of the terms used in this section, see .BR attributes (7).