Hi Arnd,
I would like to fix syscalls in Microblaze repo. Can you give me a hint how to
do it?
I think we need to do it on a case-by-case basis, best here on the
linux-arch mailing list. I'm sure there are some controversial ones,
but most should be pretty clear.
I look at Blackfin arch and I compared files with microblaze. There are some
differences but not so much.
Can you tell me how to test it which syscall is necessary for platform.
I have never found any documentation about.
Hopefully we can get to this kind of documentation by the end of this
discussion. scripts/checksyscalls.sh is some part of the documentation,
and we can refine that.
:-)
Maybe we can even have an asm-generic/unistd.h that defines all the
still relevant syscalls, plus a per-architecture range that you can
use for microblaze-specific calls in your own unistd.h.
That will be really useful. Good idea.
In my syscall_table.S (on some arch in entry.S) is one big jump table with
reference to syscalls. In unistd.h is definition.
Is there any convention which syscalls are use for all archs and which are
architecture specific?
Not really. There are very few syscalls that are needed only on certain
architectures. The more common case is that a syscall has been replaced
by a more complex interface, and a new architecture only needs one of the
two, while older architectures still need both.
Let me just comment on your syscall table as it is today:
ENTRY(sys_call_table)
.long sys_restart_syscall /* 0 - old "setup()" system call,
* used for restarting */
The comment is irrelevant and misleading -- microblaze never had sys_setup.
I removed this comment.
.long sys_exit
.long sys_ni_syscall /* was fork */
it might be useful to renumber your calls once all the irrelevant ones
have been removed, so you can get rid of all the sys_ni_syscalls here.
I'll delete all sys_ni_syscall from syscall_table.S and I'll remove it from
unistd.h too. I hope I'll keep the same call numbers.
.long sys_read
.long sys_write
.long sys_open /* 5 */
Since we have all the new sys_*at calls like openat, we don't really
need the old versions any more. The kernel implementation of sys_open
basically calls openat. You could do the same in libc instead.
Don't know if that's worth it though, opinions?
I looked at it and there are the different arguments for open and openat
syscalls. Implementation is almost the same. I keep it now.
.long sys_close
.long sys_waitpid
waitpid and wait4 can be replaced with waitid
Can I keep number of syscall(unistd.h) and only add reference to waitid in
syscall_table? or just remove?
.long sys_creat
.long sys_link
.long sys_unlink /* 10 */
.long sys_execve_wrapper
having an execve_wrapper instead of execve looks like a strange convention,
though I guess you had a good reason for it, could you explain?
This one looks architecture specific, so you may want to rename it
microblaze_execve_wrapper instead of sys_execve_wrapper.
I looked at it and the same of style is used in arm
(arch/arm/kernel/entry-common.S) and some others arch. This wrapper only set one
parameter to correct pointer to stack.
I'll comment the rest later. I need time to look at it.
Thanks for your big help. I really appreciate this.
Michal
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