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Re: [RFC] [PATCH] 32-bit pointers in x86-64
- From: "Jan Beulich" <jbeulich at novell dot com>
- To: "Paul Brook" <paul at codesourcery dot com>
- Cc: <gcc at gcc dot gnu dot org>,"Luca" <luca dot b633 at gmail dot com>, <binutils at sourceware dot org>
- Date: Mon, 26 Nov 2007 10:52:47 +0000
- Subject: Re: [RFC] [PATCH] 32-bit pointers in x86-64
>>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).