Messages in this thread | | | From | (Alan Cox) | Subject | Re: kill -9 <pid of X> | Date | Sun, 16 Aug 1998 20:50:49 +0100 (BST) |
| |
> > The bigger problems are that X11 is subject to being killed with sig 9 > > (which with a horrible kernel hack can be blocked for iopl3 processes) > > Is that so horrible? If X is going to bang hardware like kernel code, > it may as well act like kernel code.
kernel code doesnt get pre-empted without warning, killed due to lack of memory and other stuff. Its a more controlled space.
> > not that big a deal - a setuid "sak signal" ioctl akin to the way you > > take over console switching covers it. > > Yes, as long as X won't let a user remap SAK.
X shouldnt be capable of remapping SAK
> > I'd agree however - you don't need to put all mode switching code in > > kernel if you allow iopl3 proceses to lock out sig 9 and you provide > > a sak hook. Oom should be solvable its just harder > > Oom is easy: mlockall()
Bad luck X11 is designed to make good use of the paging. mlockall does work for Linus suggested mode changing daemon
> If X is going to play with hardware, then mlockall() is simply the > correct solution. X already disables interrupts sometimes. X can use > DMA too then, though a system call to get physical addresses would help.
You can't DMA to user space. To do that right is hard. Linus turned down a couple of "almost right" patches for 2.1.x so until 2.3.x if you want DMA you gotta be in the kernel.
Alan
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.altern.org/andrebalsa/doc/lkml-faq.html
| |