On Mon, Jan 21, 2019 at 9:19 AM Geert Uytterhoeven geert@linux-m68k.org wrote:
On Sat, Jan 19, 2019 at 3:29 PM Russell King - ARM Linux admin linux@armlinux.org.uk wrote:
On Fri, Jan 18, 2019 at 11:53:25AM -0800, Andy Lutomirski wrote:
On Fri, Jan 18, 2019 at 11:33 AM Arnd Bergmann arnd@arndb.de wrote:
On Fri, Jan 18, 2019 at 7:50 PM Andy Lutomirski luto@kernel.org wrote:
Can we perhaps just start the consistent numbers above 547 or maybe block out 512..547 in the new regime?
I don't think you gain much with that kind of scheme - it won't take very long before an architecture misses having a syscall added, and then someone else adds their own. Been there with ARM - I was keeping the syscall table in the same order as x86 for new syscalls, but now
Same for m68k, and probably other architectures.
that others have been adding syscalls to the table since I converted ARM to the tabular form, that's now gone out the window.
So, I think it's completely pointless to do what you're suggesting. We'll just end up with a big hole in the middle of the syscall table and then revert back to random numbering of syscalls thereafter again.
I believe the plan is to add future syscalls for all architectures in a single commit, to keep everything in sync.
Yes, that is the idea. This was not realistic before, since each one of the old architectures had its own way of describing the system call tables, and many needed a different set of quirks.
Since (almost) everything is now converted to the syscall.tbl format, we have removed all obsolete architectures, and a lot of the quirks (x32, spu, s390-31) won't matter as much in the future, I think it is now possible to do it.
We could even extend scripts/checksyscalls.sh to warn if a new syscall above 423 is not added to all 16 tables at the same time.
Regardless, I'm wondering what to do with the holes marked "room for arch specific calls". When is a syscall really arch-specific, and can it be added there, and when does it turn out (later) that it isn't, breaking the synchronization again?
We've had a bit of that already, with cacheflush(), which exists on a couple of architectures, including some that use the first 'arch specific' slot (244) of the asm-generic table. I think this will be rare enough that we can figure out a solution when we get there.
The pkey syscalls may be a bad example, as AFAIU they can be implemented on some architectures, but not on some others. Still, I had skipped them when adding new syscalls to m68k.
Perhaps we should get rid of the notion of "arch-specific syscalls", and reserve a slot everywhere anyway?
I don't mind calling the hole something else if that helps. Out of principle I would already assume that anything we add for x86 or the generic table should be added everywhere, but we can make it broader than that.
Arnd