linux-kernel - Re: [PATCH] shorten the x86_64 boot setup GDT to what the comment says

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Message-ID: <20061109154436.GA31954@mailshack.com>
Date:	Thu, 9 Nov 2006 16:44:36 +0100
From:	Alexander van Heukelum <heukelum@...lshack.com>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	LKML <linux-kernel@...r.kernel.org>, sct@...hat.com, ak@...e.de,
	herbert@...dor.apana.org.au, xen-devel@...ts.xensource.com
Subject: Re: [PATCH] shorten the x86_64 boot setup GDT to what the comment says

On Thu, Nov 09, 2006 at 10:18:53AM -0500, Steven Rostedt wrote:
> Hmm, Andi,
> 
> Should this be more like what is done in x86? Although this isn't a major
> bug or anything, would it be cleaner. For example doing:
> 
> @@ -836,11 +836,15 @@ gdt:
>         .word   0x9200                          # data read/write
>         .word   0x00CF                          # granularity = 4096, 386
>                                                 #  (+5th nibble of limit)
> +gdt_end:
> +       .align  4
> +
> +       .word   0                               # alignment byte
>  idt_48:
>         .word   0                               # idt limit = 0
>         .word   0, 0                            # idt base = 0L
>  gdt_48:
> -       .word   0x8000                          # gdt limit=2048,
> +       .word   gdt_end - gdt - 1               # gdt limit=2048,
>                                                 #  256 GDT entries
> 
>         .word   0, 0                            # gdt base (filled in
> 
> instead?

Hi!

Maybe you should consider 16-byte aligning the gdt table too, like
i386 does? It doesn't hurt, and as per the comment in the i386-file
"16 byte aligment is recommended by intel."

Greetings,
	Alexander van Heukelum

> If so, I can send you another patch that does this. Will need to test it
> first.
> 
> -- Steve
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