On Sat, Aug 15, 2020 at 09:11:40AM -0700, Bart Van Assche wrote: > On 2020-08-15 07:14, Magnus Fromreide wrote: > > This allows vfork to not block the parent until the child has called _exit > > or exec*, it does not allow the child to block the parent until completion. > > > > Please note that in our case this is arch-specific code for uClinux where > > the fork() system call doesn't exist so I think we can be assured that vfork > > will block the parent there. > > On > https://www.eetimes.com/how-uclinux-provides-mmu-less-processors-with-an-alternative/# > I found the following, which confirms the above: > > uClinux implements vfork() in order to compensate for the lack of fork(). > When a parent process calls vfork() to create a child, both processes share > all their memory space including the stack. vfork() then suspends the > parent's execution until the child process either calls exit() or execve(). > > > If we had been religous about marking all internal fd's as CLOEXEC then > > pass_perrsistant could be rewritten using posix_spawn which sounds a lot > > better but we are sadly lacking in the CLOEXEC department. > > > > To be honest the calls to perror and exit if exec fails is more suspicious > > as > > that is explicitly stated to cause undefined behaviour. > > > > With all this I should probably repeat that I am in favour of dropping the > > pass_persist support for uClinux. > > How about removing the pass_persist for uClinux and restoring it if a > user asks to restore that support? uClinux was created in 1998, when > the price difference between microprocessors with or without MMU was > much larger than today. Today a Raspberry Pi is available for $35. That > product includes not only a CPU with MMU but also a board and connectors.
That is a more lenient option than just dropping it so I think 'happy with dropping it' covers this variant. On the other hand I usually am far from the most conservative one in discussions like this one. /MF _______________________________________________ Net-snmp-coders mailing list Net-snmp-coders@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/net-snmp-coders
