How about the following (untested, not even compiled):
-- Cheers, Stephen Rothwell sfr@canb.auug.org.au http://www.canb.auug.org.au/~sfr/diff -ruN 2.5.31/arch/i386/kernel/apm.c 2.5.31-apm.1/arch/i386/kernel/apm.c --- 2.5.31/arch/i386/kernel/apm.c 2002-08-02 11:11:34.000000000 +1000 +++ 2.5.31-apm.1/arch/i386/kernel/apm.c 2002-08-13 00:20:56.000000000 +1000 @@ -215,6 +215,7 @@ #include <linux/pm.h> #include <linux/kernel.h> #include <linux/smp_lock.h> +#include <linux/smp.h> #include <asm/system.h> #include <asm/uaccess.h> @@ -419,6 +420,7 @@ static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue); static struct apm_user * user_list; static spinlock_t user_list_lock = SPIN_LOCK_UNLOCKED; +static struct desc_struct bad_bios_desc = { 0, 0x00409200 }; static char driver_version[] = "1.16"; /* no spaces */ @@ -569,7 +571,12 @@ { APM_DECL_SEGS unsigned long flags; + int cpu; + struct desc_struct save_desc_40; + cpu = get_cpu(); + save_desc_40 = cpu_gdt_table[cpu][0x40 / 8]; + cpu_gdt_table[cpu][0x40 / 8] = bad_bios_desc; local_save_flags(flags); APM_DO_CLI; APM_DO_SAVE_SEGS; @@ -591,6 +598,8 @@ : "memory", "cc"); APM_DO_RESTORE_SEGS; local_irq_restore(flags); + cpu_gdt_table[cpu][0x40 / 8] = save_desc_40; + put_cpu(); return *eax & 0xff; } @@ -613,7 +622,12 @@ u8 error; APM_DECL_SEGS unsigned long flags; + int cpu; + struct desc_struct save_desc_40; + cpu = get_cpu(); + save_desc_40 = cpu_gdt_table[cpu][0x40 / 8]; + cpu_gdt_table[cpu][0x40 / 8] = bad_bios_desc; local_save_flags(flags); APM_DO_CLI; APM_DO_SAVE_SEGS; @@ -639,6 +653,8 @@ } APM_DO_RESTORE_SEGS; local_irq_restore(flags); + cpu_gdt_table[smp_processor_id()][0x40 / 8] = save_desc_40; + put_cpu(); return error; } @@ -1923,17 +1939,14 @@ * that extends up to the end of page zero (that we have reserved). * This is for buggy BIOS's that refer to (real mode) segment 0x40 * even though they are called in protected mode. - * - * NOTE: on SMP we call into the APM BIOS only on CPU#0, so it's - * enough to modify CPU#0's GDT. */ - for (i = 0; i < NR_CPUS; i++) { - set_base(cpu_gdt_table[i][APM_40 >> 3], - __va((unsigned long)0x40 << 4)); - _set_limit((char *)&cpu_gdt_table[i][APM_40 >> 3], 4095 - (0x40 << 4)); + set_base(bad_bios_desc, __va((unsigned long)0x40 << 4)); + _set_limit((char *)&bad_bios_desc, 4095 - (0x40 << 4)); + + apm_bios_entry.offset = apm_info.bios.offset; + apm_bios_entry.segment = APM_CS; - apm_bios_entry.offset = apm_info.bios.offset; - apm_bios_entry.segment = APM_CS; + for (i = 0; i < NR_CPUS; i++) { set_base(cpu_gdt_table[i][APM_CS >> 3], __va((unsigned long)apm_info.bios.cseg << 4)); set_base(cpu_gdt_table[i][APM_CS_16 >> 3], diff -ruN 2.5.31/arch/i386/kernel/head.S 2.5.31-apm.1/arch/i386/kernel/head.S --- 2.5.31/arch/i386/kernel/head.S 2002-07-28 21:11:25.000000000 +1000 +++ 2.5.31-apm.1/arch/i386/kernel/head.S 2002-08-13 00:29:38.000000000 +1000 @@ -427,7 +427,10 @@ * The APM segments have byte granularity and their bases * and limits are set at run time. */ - .quad 0x0040920000000000 /* 0x40 APM set up for bad BIOS's */ + .quad 0x0000000000000000 /* 0x40 APM will be used for bad BIOS's + * Will be saved and restored + * across BIOS calls. MUST NOT BE ONE + * OF THE FOLLOWING THREE! */ .quad 0x00409a0000000000 /* 0x48 APM CS code */ .quad 0x00009a0000000000 /* 0x50 APM CS 16 code (16 bit) */ .quad 0x0040920000000000 /* 0x58 APM DS data */ diff -ruN 2.5.31/include/linux/apm_bios.h 2.5.31-apm.1/include/linux/apm_bios.h --- 2.5.31/include/linux/apm_bios.h 2001-08-14 09:39:28.000000000 +1000 +++ 2.5.31-apm.1/include/linux/apm_bios.h 2002-08-13 00:38:52.000000000 +1000 @@ -21,8 +21,7 @@ #ifdef __KERNEL__ -#define APM_40 0x40 -#define APM_CS (APM_40 + 8) +#define APM_CS 0x48 #define APM_CS_16 (APM_CS + 8) #define APM_DS (APM_CS_16 + 8) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/