From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 8 Oct 2008 00:40:30 +0100 From: Alan Cox Subject: Re: [PATCH, v3] shmat: introduce flag SHM_MAP_NOT_FIXED Message-ID: <20081008004030.7a0e9915@lxorguk.ukuu.org.uk> In-Reply-To: <20081007232059.GU20740@one.firstfloor.org> References: <1223396117-8118-1-git-send-email-kirill@shutemov.name> <2f11576a0810070931k79eb72dfr838a96650563b93a@mail.gmail.com> <20081007211038.GQ20740@one.firstfloor.org> <20081008000518.13f48462@lxorguk.ukuu.org.uk> <20081007232059.GU20740@one.firstfloor.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andi Kleen Cc: KOSAKI Motohiro , "Kirill A. Shutemov" , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Ingo Molnar , Arjan van de Ven , Hugh Dickins , Ulrich Drepper , Andrew Morton List-ID: > > Can use shm_open and mmap to get POSIX standard shm behaviour via a sane > > I don't think shm_open can attach to SYSV shared segments. Or are you > proposing to add "sysvshmfs" to make that possible? Actually you can do so. As it stands today the SYS3 SHM interface code does the following create a char array in the form SYS%08ld, key open it on shmfs > - There are legacy interfaces that cannot be really changed who use sysv shm > (e.g. X shm and others -- just do a ipcs on your system) They can be changed and nobody is wanting to map those at fixed addresses. > - An system call emulation as in qemu obviously has to implement the > existing system call semantics. Which it can do perfectly well using shm_open to create its SYS3 SHM objects. In fact theoertically we could bin the whole of SYS3 shm and push it into glibc emulation if we wanted. Alan -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org