On 09/05/2013 04:50 PM, Anthony Liguori wrote: >> + int *p = NULL; >> + >> + *p = 0xDEADBEEF; > > I won't repeat the questions from Paolo and Lazlo (I share their > confusion) but will simply add that you cannot rely on NULL address > accessing causing a SEGV. Even with all the use of volatile in the > world, there's no guarantee this is going to crash.
If you want to guarantee that a write would cause a SEGV, then you have to use mmap(MAP_ANONYMOUS|MAP_PRIVATE) + mprotect(PROT_NONE) to get a valid unwritable pointer that will reliably fault, rather than hoping that NULL (or any other low-valued intptr_t cast to void*) is sufficiently protected. But I also echo the question: why is raise() insufficient? -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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