Re: [Qemu-devel] ?==?utf-8?q? ?==?utf-8?q? [PATCH 0/5]?==?utf-8?q? linux-user: Support signal passing for targets having more signals than host

[Milos Stojanovic]

Hello, Peter.
For this implemenation rt_sigqueueinfo()/rt_tgsigqueueinfo() were used to 
multiplex signals that are out of the host range. This enabled the use of a 
wider signal range with rt_sigqueueinfo(), rt_tgsigqueueinfo(), as well as 
kill() (for pid > 0) and tgkill(). A process can now use these system calls to 
send a range of signals which weren't supporeted before to itself or others 
threads or processes.

The tkill() system call and kill() with the argument pid <= 0 couldn't be 
implemented simply using this method because it requires acquiring information 
about, and sending simultaneous signals to multiple threads or processes and 
these functionalities are out of the scope of 
rt_sigqueueinfo()/rt_tgsigqueueinfo().

This patch set was primarily focused on expanding the range of real-time 
signals and making them usable but some limitations still remain. For example, 
the priority of those real-time signals, as defined by POSIX, doesn't depend on 
the actual signal number but on the host signal nuber which is used for 
multiplexing.
As it now is, the functionaly is only enabled for signals that are 
higher-numbered then the host signals but I don't see a conceptual problem in 
expanding and testing the implenentation to include other signals (e.g. the 
signals that NPTL uses).

Regards,
Miloš