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Diffstat (limited to 'system_call.mdwn')
| -rw-r--r-- | system_call.mdwn | 45 |
1 files changed, 44 insertions, 1 deletions
diff --git a/system_call.mdwn b/system_call.mdwn index 16d706c7..45ed9dbe 100644 --- a/system_call.mdwn +++ b/system_call.mdwn @@ -1,4 +1,5 @@ -[[!meta copyright="Copyright © 2010, 2013 Free Software Foundation, Inc."]] +[[!meta copyright="Copyright © 2010, 2013, 2014 Free Software Foundation, +Inc."]] [[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable id="license" text="Permission is granted to copy, distribute and/or modify this @@ -33,3 +34,45 @@ system call is implemented (primarily by means of [[RPC]]) inside [[glibc]]. provide system services <braunr> e.G. open() is a call to a file system server (and maybe several actually) + + +# IRC, freenode, #hurd, 2013-11-02 + + <Hiryu> how do system calls work in the hurd? + <Hiryu> is it like in linux + <braunr> yes and no + <Hiryu> you set the number in %eax and then in0x80? + <Hiryu> int, even + <braunr> no + <braunr> but that's really a detail + <Hiryu> I'm just curious how the flow goes + <braunr> gnumach uses call gates, not interrupt gates + <braunr> but that's just another way to enter the kernel + <braunr> the mechanism itself is almost irrelevant, it matters only for + performances + <Hiryu> ah + <braunr> what's truely interesting is that there are very few system calls + <Hiryu> so it goes straight to gnumach, which then figures out where to + relay the call to? + <braunr> the main one being mach_msg + <braunr> yes + <braunr> one of the arguments to mach_msg is the name of a right + <braunr> (as file descriptors are names for open files) + <Hiryu> hmm okay, so we get to the kernel, go to a kernel server (one + context switch), then get back to the calling process, and that's 2 + context switches per system call? + <braunr> a receive right or send right + <braunr> no + <braunr> if you send-recv, it's only one + <braunr> but i'm not sure we do that on the hurd + <braunr> again, that's a detail + <Hiryu> what is send-recv? + <braunr> send and receive in the same system call + <Hiryu> hmm + <braunr> then, we also use system calls to denote the unix-like RPCs of the + hurd + <braunr> i mean + <braunr> i also call them system calls + <braunr> for example, read, write, stat, etc.. + <Hiryu> I see + <Hiryu> braunr: thanks |