Date: Mon, 17 Jul 2006 12:29:22 -0500 From: "Christian S.J. Peron" <csjp@FreeBSD.org> To: John Baldwin <jhb@freebsd.org> Cc: Igor Sysoev <is@rambler-co.ru>, freebsd-current@freebsd.org Subject: Re: 2Gb SYSVSHM limitation Message-ID: <44BBC8F2.3010807@FreeBSD.org> In-Reply-To: <200607171256.00539.jhb@freebsd.org> References: <20060712125112.W61255@is.park.rambler.ru> <200607171256.00539.jhb@freebsd.org>
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John Baldwin wrote: > On Wednesday 12 July 2006 04:58, Igor Sysoev wrote: > >> Hi, >> >> the current kernel limit of SysV memory segment is 2G. >> Today it is too small for amd64 machines. >> >> Year ago Christian S.J. Peron had propsed the patch >> http://people.freebsd.org/~csjp/bigsharedmem.1117028863.diff >> to increase the limit: >> http://freebsd.rambler.ru/bsdmail/freebsd-current_2005/msg05627.html >> >> Are objections against this patch ? >> > > Well, it breaks the ABI of shminfo. :( Changing the ABI of structures shared > with userspace like this requires duplicate syscalls, etc. to not break > existing binaries (such as existing 6.x amd64 binaries). > > I committed this patch, I just have not MFCed it. The ABI breakage is un-clear: I change this structure which should be kernel private, and I dont think we make any guarantees here. We do export this kernel private structure through shmctl(IPC_INFO), however IPC_INFO is not standard. #ifdef _KERNEL /* * System 5 style catch-all structure for shared memory constants that * might be of interest to user programs. Do we really want/need this? */ struct shminfo { int shmmax, /* max shared memory segment size (bytes) */ shmmin, /* min shared memory segment size (bytes) */ shmmni, /* max number of shared memory identifiers */ shmseg, /* max shared memory segments per process */ shmall; /* max amount of shared memory (pages) */ }; I changed these from int to long iirc -- Christian S.J. Peron csjp@FreeBSD.ORG FreeBSD Committer FreeBSD Security Team
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