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i386: extra descriptors in GDTs not needed?
- From: David Vrabel <dvrabel at arcom dot com>
- To: ecos-discuss at ecos dot sourceware dot org
- Date: Mon, 17 Jan 2005 10:44:10 +0000
- Subject: [ECOS] i386: extra descriptors in GDTs not needed?
Hi,
Various places in the i386 HAL have GDTs containing the following extra
descriptors in the GDT (e.g. hal/i386/arch/current/src/vectors.S,
hal/i386/pc/current/include/platform.inc):
/* Selector 0x18 == shorter code: faults any code
* access 0xF0000000-0xFFFFFFFF.
*/
.word 0xFFFF
.word 0x0000
.byte 0x00
.byte 0x9B
.byte 0xC7
.byte 0x00
/* Selector 0x20 == data; faults any access
0xF0000000-0xFFFFFFFF. */
.word 0xFFFF
.word 0x0000
.byte 0x00
.byte 0x93
.byte 0xC7
.byte 0x00
Are these descriptors actually used anywhere? Or can they be removed?
They don't seem particularly useful.
David Vrabel
--
David Vrabel, Design Engineer
Arcom, Clifton Road Tel: +44 (0)1223 411200 ext. 3233
Cambridge CB1 7EA, UK Web: http://www.arcom.com/
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