2024-10-22 07:41 (UTC-0500), Lewis Donzis: > I've been wondering why we exclude memory allocated by > eal_get_virtual_area() from core dumps? (More specifically, it calls > eal_mem_set_dump() to call madvise() to disable core dumps from the > allocated region.) > > On many occasions, when debugging after a crash, it would have been very > convenient to be able to see the contents of an mbuf or other object > allocated in contigmem space. And we often avoid using the rte memory > allocator just because of this. > > Is there any reason for this, or could it perhaps be a compile-time > configuration option not to call madvise()?
The commit that originally added madvise() argued that dumping everything ended up in coredumps with "useless" data [non-mapped or unused pages]: http://git.dpdk.org/dpdk/commit/?id=d72e4042c5ebda7af81448b387af8218136402d0 Dumping mapped pages sounds reasonable in many cases. Not in all cases admittedly: - legacy memory mode mapping a lot of pages that are not (yet) used; - if packet data is confidential while the app is not. The option to dump or not can easily be a runtime one. The safe default however seems to be "off". In dynamic memory node (not FreeSBD, unfortunately) rte_mem_event_callback-register() may be used to call madvise(). Maybe DPDK should allow such callbacks in any mode and invoke them during initialization to make the above solution universal.
