Re: [PATCH v2 2/3] Add an optional "alias" attribute to syscall entries.

[Simon Marchi <simon.marchi@polymtl.ca>]

On 2018-11-09 10:28, Simon Marchi wrote:
> On 2018-11-06 12:54, John Baldwin wrote:
>> When setting a syscall catchpoint by name, catch syscalls whose name
>> or alias matches the requested string.
>> 
>> When the ABI of a system call is changed in the FreeBSD kernel, this
>> is implemented by leaving a compatibility system call using the old
>> ABI at the existing "slot" and allocating a new system call for the
>> version using the new ABI.  For example, new fields were added to the
>> 'struct kevent' used by the kevent() system call in FreeBSD 12.  The
>> previous kevent() system call in FreeBSD 12 kernels is now called
>> freebsd11_kevent() and is still used by older binaries compiled
>> against the older ABI.  The freebsd11_kevent() system call can be
>> tagged with an "alias" attribute of "kevent" permitting 'catch syscall
>> kevent' to catch both system calls and providing the expected user
>> behavior for both old and new binaries.  It also provides the expected
>> behavior if GDB is compiled on an older host (such as a FreeBSD 11
>> host).
> 
> Will we ever need to provide more than one alias to a syscall?

Sorry, I just saw you have already answered this question, here:

https://sourceware.org/ml/gdb-patches/2018-10/msg00385.html

Simon