From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: Why don't we make mmap MAP_SHARED with /dev/zero possible? References: <199910260158.JAA00043@chpc.ict.ac.cn> Mime-Version: 1.0 (generated by tm-edit 7.108) Content-Type: text/plain; charset=US-ASCII From: Christoph Rohland Date: 26 Oct 1999 09:35:45 +0200 In-Reply-To: fxzhang's message of "Tue, 26 Oct 1999 9:57:48 +0800" Message-ID: Sender: owner-linux-mm@kvack.org Return-Path: To: fxzhang@chpc.ict.ac.cn Cc: "linux-mm@kvack.org" List-ID: fxzhang writes: > and find this: > /usr/src/linux/drivers/char/mem.c static int mmap_zero(struct file * > file, struct vm_area_struct * vma) { > if (vma->vm_flags & VM_SHARED) > return -EINVAL; > > I don't understand why people don't implement it.Yes,in the source,I > find something like "the shared case is complex",Could someone tell me > what's the difficulty?As it is a driver,I think it should not be too > much to concern.At least I know in Solaris this works. > I want to implement it but know I am not competent now,I am just > beginning digging it:). Yes I would like to see it also, but at least in 2.0 days it was really difficult/impossible. > Is there any good way to share memory between process at page > granularity?That is,I can share individual pages between them? Threads > maybe a subtitue,but there are many things that I don't want to share. Using SYSV shm with key IPC_PRIVATE gives you the same behaviour. Greetings Christoph -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://humbolt.geo.uu.nl/Linux-MM/