Date: Tue, 14 Jan 2003 22:33:47 -0600 From: "Alan L. Cox" <alc@imimic.com> To: Marcel Moolenaar <marcel@xcllnt.net> Cc: Peter Wemm <peter@wemm.org>, Matthew Dillon <dillon@apollo.backplane.com>, arch@FreeBSD.ORG Subject: Re: Virtual memory question Message-ID: <3E24E4AB.5B50EBD6@imimic.com> References: <20030114041407.DDFC32A89E@canning.wemm.org> <3E239150.9FC363DD@imimic.com> <20030114100022.GA17799@dhcp01.pn.xcllnt.net>
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Marcel Moolenaar wrote:
>
> On Mon, Jan 13, 2003 at 10:25:52PM -0600, Alan L. Cox wrote:
> >
> > >From the spec (on the web page that I mentioned):
> >
> > "The name argument points to a string naming a shared memory object. It
> > is unspecified whether the name appears in the file system and is
> > visible to other functions that take pathnames as arguments."
> >
> > I don't think ftruncate() is necessary. The underlying shm object can
> > be grown implicitly according to its mmap()ings. I do not, however,
> > know of a way to shrink an shm object.
>
> shm_open("key", O_TRUNC|..., ...) ?
>
Yes, that is defined to reset the object to zero length. I was thinking
about something that would only eliminate a portion of the object.
Alan
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