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>