I'd like to add a signal mask to kvm, so that when the guest executes, the signal mask is temporarily set to some user specified value. This allows signals to be used as a way to interrupt the guest, but without requiring signal delivery to the userspace handler (which is what makes signals expensive).
The question is how to fit the signal mask to the kvm userspace interface (which has a shared kernel/user structure that userspace mmaps). I see several options: 1. Add a __u64 to that structure. This is the simplest option, but I see that signal masks in the kernel/user interface are variable-length bitmaps, so this clearly doesn't work well. 2. Add __u32 signal_mask_offset and signal_mask_size members to the structure to tell userspace where to store the signal mask (in the same shared area). A disadvantage is that here the kernel tells the user the size of the signal mask instead of the other way round as is traditional. 3. Add a separate ioctl to set the signal mask. A NULL parameter disables the signal mask functionality. I am in favor of the third option, but the existence of three options tells me more are possible. [Just as background, signals are used for the following in our modified qemu, the only known public client for kvm: - interrupt the guest to get timer interrupts - interrupt the guest on packet arrival - interrupt the guest on aio completion - (future) for guest smp, to simulate IPIs] -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ kvm-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/kvm-devel
