From: Benjamin Herrenschmidt <bh40@calva.net>
To: FASSINO Jean-Philippe
<jeanphilippe.fassino@cnet.francetelecom.fr>,
linuxppc-dev@lists.linuxppc.org
Subject: Re: eieio & ld_le, ld_be
Date: Tue, 22 Feb 2000 15:24:43 +0100 [thread overview]
Message-ID: <20000222152443.010969@mailhost.mipsys.com> (raw)
On Tue, Feb 22, 2000, FASSINO Jean-Philippe
<jeanphilippe.fassino@cnet.francetelecom.fr> wrote:
>Just a question about ld_le* and ld_be*.
>This function do a io read and enforce in-order execution with eieio.
>
>Does eieio is really necessary when load value from IO ??
>Maybe some computer (SMP, pci, ...) require that !
>But, i try ld_* without eieio on my computer (G4) and that work well.
Neither ld_le* nor ld_be* should do any eieio (and they don't in the
kernel sources I just checked).
Howeverm in_le*/out_le* etc... do it. Those are necessary to enforce
ordering of accesses when manipulating a hardware device. It's possible
that the non-cachable & guarded state of io pages make it less important
on G3, but it's definitely necessary to be completely safe.
If you are maniuplating in-memory datas that are not related to any io
hardware device, then you don't need eieio.
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
next reply other threads:[~2000-02-22 14:24 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-02-22 14:24 Benjamin Herrenschmidt [this message]
2000-02-22 17:59 ` eieio & ld_le, ld_be Gabriel Paubert
-- strict thread matches above, loose matches on Subject: below --
2000-02-22 11:49 FASSINO Jean-Philippe
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