From: "Jan Beulich" <jbeulich@novell.com>
To: "Paul Brook" <paul@codesourcery.com>
Cc: <gcc@gcc.gnu.org>,"Luca" <luca.b633@gmail.com>,
<binutils@sourceware.org>
Subject: Re: [RFC] [PATCH] 32-bit pointers in x86-64
Date: Mon, 26 Nov 2007 15:36:00 -0000 [thread overview]
Message-ID: <474AB38F.76E4.0078.0@novell.com> (raw)
>>You can't use conventional 32-bit x86 code, so there seems little or no
>>benefit in allowing 32 and 64-bit code to be mixed.
>
>Why not? Switching between 32- and 64-bit modes doesn't involve anything
>(apart from knowing the proper selector register values) that cannot be done
>purely in user mode. Specifically, I once successfully tried executing 64-bit
>code in a 32-bit process.
Oh, I didn't see the original post first (the spam filter ate it for some reason).
Of course, if the intention of running this in 64-bit mode makes my comment
void (except for the rumor-like thing I heard a few times that there's an
undocumented EFER bit allowing x86-32 mode in the sense intended here,
but that again would require a kernel running in the same mode underneath).
Jan
next reply other threads:[~2007-11-26 10:51 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-26 15:36 Jan Beulich [this message]
-- strict thread matches above, loose matches on Subject: below --
2007-11-25 18:45 Luca
2007-11-26 3:14 ` Paul Brook
2007-11-26 12:53 ` Jan Beulich
2007-11-26 3:40 ` Andrew Pinski
2007-12-05 9:31 ` Jan Beulich
2007-12-05 10:48 ` Andrew Pinski
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