On 9/9/05, Steven J. Magnani <steve@digidescorp.com> wrote:

I posted this patch previously; see
http://openbios.org/pipermail/linuxbios/2005-August/012063.html for the
original issue.

Here's another chance to comment before I commit it.

PATCH:

--- src/arch/i386/boot/tables.c.orig    2005-09-08 13:35:39.125000000
-0500
+++ src/arch/i386/boot/tables.c 2005-08-16 16:17:41.766000000 -0500
@@ -7,6 +7,32 @@
#include <arch/acpi.h>
#include "linuxbios_table.h"

+// Global Descriptor Table, defined in c_start.S
+extern uint8_t gdt;
+extern uint8_t gdt_end;
+
+/* i386 lgdt argument */
+struct gdtarg {
+    unsigned short limit;
+    unsigned int base;
+} __attribute__((packed));
+
+// Copy GDT to new location and reload it
+// 2003-07 by SONE Takeshi
+// Ported from Etherboot to LinuxBIOS 2005-08 by Steve Magnani
+void move_gdt(unsigned long newgdt)
+{
+       uint16_t num_gdt_bytes = &gdt_end - &gdt;
+    struct gdtarg gdtarg;
+
+    printk_debug("Moving GDT to %#lx...", newgdt);
+    memcpy((void*)newgdt, &gdt, num_gdt_bytes);
+    gdtarg.base = newgdt;
+    gdtarg.limit = num_gdt_bytes - 1;
+    __asm__ __volatile__ ("lgdt %0\n\t" : : "m" (gdtarg));
+    printk_debug("ok\n");
+}
+
struct lb_memory *write_tables(void)
{
        unsigned long low_table_start, low_table_end;
@@ -45,6 +71,10 @@
                low_table_end = 0x500;
        }

+       // Relocate the GDT to reserved memory, so it won't get
clobbered
+       move_gdt(low_table_end);
+       low_table_end += &gdt_end - &gdt;
+
        /* The linuxbios table must be in 0-4K or 960K-1M */
        write_linuxbios_table(
                              low_table_start, low_table_end,

------------------------------------------------------------------------
Steven J. Magnani               "I claim this network for MARS!
www.digidescorp.com              Earthling, return my space modulator!"

#include <standard.disclaimer>

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