Date: Tue, 19 Feb 2002 09:34:04 -0800 From: "mike varga" <mike.varga@cavium.com> To: "Michael Smith" <msmith@freebsd.org> Cc: <freebsd-arch@freebsd.org> Subject: Re: reverse vtophys() Message-ID: <004f01c1b96b$a37d1f50$b210a8c0@netscreen5> References: <200202170813.g1H8DAV01750@mass.dis.org>
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The concept is valid in Linux, there is a function that does what I am asking. bus_to_virtual(). The page is locked in memory. Therefor there is one valid page backed by the physical address that corresponds to the virtual address that I am interested in retrieving? ----- Original Message ----- From: "Michael Smith" <msmith@freebsd.org> To: "mike varga" <mike.varga@cavium.com> Cc: <freebsd-arch@freebsd.org> Sent: Sunday, February 17, 2002 12:13 AM Subject: Re: reverse vtophys() > > > > Is there a function that exists=20 > > that converts a physical address to=20 > > a process's virtual address? > > No; the concept isn't valid. > > - A given physical address may be mapped in more than one virtual > location within the process' address space. > > - There is an unavoidable race with unwired memory where a physical > page may "move" as it is used to back more than a single physical > page, resulting in a bad answer. > > Perhaps you should explain what it is that you're trying to do, rather > than narrowing down to what you think is the solution... > > -- > To announce that there must be no criticism of the president, > or that we are to stand by the president, right or wrong, is not > only unpatriotic and servile, but is morally treasonable to > the American public. - Theodore Roosevelt > > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-arch" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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