On 5/11/13 1:23 AM, Karl Dreger wrote:
I am feeling rather stupid at the moment, but I can't find the assembler
files that you are referring to. Do you mean that every syscall under
sys/kern/*.c has a corresponding .S file in src/lib/libc/?
Nope, the .S files are under the object directory:
When you build the system a whole bunch of assembler files are
automatically generated that define the functions you are looking for.
Look for .S files under the object directory.
Those assembler files have the magic to cause a system call to happen.
example: src/lib/libc/getauid.S (note, this file is GENERATED, it's not
part of src.)
The actual transition from user to kernelland and back probably takes
place via the assembler routines in sys/i386/i386. Most notably exception.s
for my i386 cpu.
What my question boils down to is this: when running fork and friends
from userland they are invoked as:
fork();, open();, read();, close(); ...
but are defined as:
sys_fork(), sys_open(), sys_read(), sys_close(), ...
in their actual c definition.
If the assembler files that you spoke about answer this discrepancy,
then the reason why the penny hasn't dropped yet is because I haven't
found them.
Again, they are generated as part of build. You will NOT find them
during a checkout.
-Alfred
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