Re: [PATCH v3 2/3] Add an optional "alias" attribute to syscall entries.

[John Baldwin <jhb at FreeBSD dot org>]

On 11/28/18 10:34 AM, Pedro Alves wrote:
> On 11/28/2018 06:00 PM, John Baldwin wrote:
>> On 11/28/18 9:44 AM, Eli Zaretskii wrote:
>>>> Cc: gdb-patches@sourceware.org
>>>> From: John Baldwin <jhb@FreeBSD.org>
>>>> Date: Wed, 28 Nov 2018 09:22:22 -0800
>>>>
>>>> Yes, I think this is better as well.  Eli, I don't know if other OS's will
>>>> make use of this feature.  Given Pedro's new text above, do you think it
>>>> should still be moved into a native section or should it stay in the the
>>>> syscall section?
>>>
>>> I question the need to make this text more general than this feature
>>> will ever become.  But if Pedro thinks we will have similar aliases on
>>> other OSes, then sure, do it as Pedro suggests.
> 
> Don't other BSD kernels do something similar?

Hmm, it is true that 4.4BSD itself included some compat system calls to handle
some ABI changes which is why the BSD's follow that model.  NetBSD at least
follows FreeBSD's model of renaming old system calls and adding new numbers for
new ABIs.  OpenBSD kind of does, but it retires older ABIs more aggressively
and seems to reuse old numbers unlike FreeBSD and NetBSD.

> I think Linux always adds new syscalls under a new name, even if the
> old replaced one is deprecated.
> 
>> Oh, I was just referring to Pedro's version being shorter.  I'm fine with
>> moving it.  This is a bit longer as it restores a bit of the FreeBSD-specific
>> note about syscall ABIs but that seemed relevant when moving it:
> I'm fine with it as well.  It just felt like if the we could keep it short, it'd
> avoid fragmenting the information.  IMO, a user reading the "catch syscall"
> bits in the manual isn't going to remember to look up the FreeBSD-specific info
> in a different node.  Unless we add some xrefs.

Yes, that is why I started with it in the syscall section.

-- 
John Baldwin