RE: [suse-sparc] 64 bit Kernel 32 bit userland.

From: Andrew Hooper (Andrew.Hooper@VITAL-NS.com)
Date: Mon Feb 18 2002 - 08:26:36 PST

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From: Andrew Hooper <Andrew.Hooper@VITAL-NS.com>
Date: Mon, 18 Feb 2002 16:26:36 -0000
Subject: RE: [suse-sparc] 64 bit Kernel 32 bit userland.

    Thanks very much..
    So there is no advantage to using 64 bit maths operations for example?

    Andrew

    > -----Original Message-----
    > From: Alvaro Figueroa <fede2@fuerzag.ulatina.ac.cr>@VITALNETSVC
    > Sent: 18 February 2002 16:02
    > To: SuSE sparc port list
    > Subject: Re: [suse-sparc] 64 bit Kernel 32 bit userland.
    >
    > <<...OLE_Obj...>>
    >
    > > Stupid Question....
    >
    > No it isnt. Quite an interesting topic BTW.
    >
    > > But, The kernel uses 64 bit instructions on Sparc Ultras and the user
    > > applications use 32 bit instructions, is this because Linux can't
    > support 64
    > > bit applications or can applications only access a 32 bit address space?
    >
    > This is because, it has been set up this way.
    >
    > The kernel does support 64 bit aplications, and aplications can access
    > the 64 bit address space, but they need to be compiled[1] as 64 bit
    > aplications.
    >
    > The reason why this has been set up this way, is because a 64 bit
    > userland will be slower that a 32 bit userland, because they need to map
    > those _large_ 64 bit adresses. The only cases in which you will need 64
    > bit aplications is when you have (for example) a *huge* database.
    >
    > I really don't know if there is any adventages in running processes in a
    > 64 bit userland. You just don't compile stuff in 64 bits because you
    > arch will handle them...
    >
    >
    > > So
    > > how do I know applications I compile are 32 bit or 64 bit?
    > > Can someone point me at an explanation of what's going on?
    >
    > Using "file". This will show output like
    > ELF 32-bit MSB executable, SPARC, version 1, blah, blah
    >
    > or
    >
    > ELF 64-bit MSB executable, SPARC V9, version 1, blah, blah
    >
    > To compile this aplications you need a cross compiler that will do the
    > job. As usual, I don't have an idea if SuSE has a package with this
    > compiler in it ;)
    >
    > [1] Or cross compiled if you will
    >
    > --
    > Alvaro Figueroa
    >
    >
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