diff options
Diffstat (limited to 'arch/i386/kernel/head.S')
| -rw-r--r-- | arch/i386/kernel/head.S | 27 |
1 files changed, 17 insertions, 10 deletions
diff --git a/arch/i386/kernel/head.S b/arch/i386/kernel/head.S index e437fb36749..5884469f6bf 100644 --- a/arch/i386/kernel/head.S +++ b/arch/i386/kernel/head.S @@ -504,19 +504,24 @@ ENTRY(cpu_gdt_table) .quad 0x0000000000000000 /* 0x80 TSS descriptor */ .quad 0x0000000000000000 /* 0x88 LDT descriptor */ - /* Segments used for calling PnP BIOS */ - .quad 0x00c09a0000000000 /* 0x90 32-bit code */ - .quad 0x00809a0000000000 /* 0x98 16-bit code */ - .quad 0x0080920000000000 /* 0xa0 16-bit data */ - .quad 0x0080920000000000 /* 0xa8 16-bit data */ - .quad 0x0080920000000000 /* 0xb0 16-bit data */ + /* + * Segments used for calling PnP BIOS have byte granularity. + * They code segments and data segments have fixed 64k limits, + * the transfer segment sizes are set at run time. + */ + .quad 0x00409a000000ffff /* 0x90 32-bit code */ + .quad 0x00009a000000ffff /* 0x98 16-bit code */ + .quad 0x000092000000ffff /* 0xa0 16-bit data */ + .quad 0x0000920000000000 /* 0xa8 16-bit data */ + .quad 0x0000920000000000 /* 0xb0 16-bit data */ + /* * The APM segments have byte granularity and their bases - * and limits are set at run time. + * are set at run time. All have 64k limits. */ - .quad 0x00409a0000000000 /* 0xb8 APM CS code */ - .quad 0x00009a0000000000 /* 0xc0 APM CS 16 code (16 bit) */ - .quad 0x0040920000000000 /* 0xc8 APM DS data */ + .quad 0x00409a000000ffff /* 0xb8 APM CS code */ + .quad 0x00009a000000ffff /* 0xc0 APM CS 16 code (16 bit) */ + .quad 0x004092000000ffff /* 0xc8 APM DS data */ .quad 0x0000920000000000 /* 0xd0 - ESPFIX 16-bit SS */ .quad 0x0000000000000000 /* 0xd8 - unused */ @@ -525,3 +530,5 @@ ENTRY(cpu_gdt_table) .quad 0x0000000000000000 /* 0xf0 - unused */ .quad 0x0000000000000000 /* 0xf8 - GDT entry 31: double-fault TSS */ + /* Be sure this is zeroed to avoid false validations in Xen */ + .fill PAGE_SIZE_asm / 8 - GDT_ENTRIES,8,0 |