diff options
| author | Samuel Thibault <samuel.thibault@ens-lyon.org> | 2014-07-06 18:49:55 +0200 |
|---|---|---|
| committer | Samuel Thibault <samuel.thibault@ens-lyon.org> | 2014-07-06 18:49:55 +0200 |
| commit | 859c342d11a2d018e7b220e955bbe1ba1940f02f (patch) | |
| tree | 1890b0757459549938be3ee5f2d23fcdcc94b019 | |
| parent | 97447914d6dcc32ada4ee028e1e2bab262501316 (diff) | |
Do not unmap page 0 when not needed
Since we need it to access some BIOS information, e.g. at ACPI shutdown. When
the kernel VM is not starting at 0, there is already nothing mapped there in
user tasks, anyway.
* i386/i386at/model_dep.c (machine_init) [VM_MIN_KERNEL_ADDRESS != 0]:
Do not call pmap_unmap_page_zero.
* i386/intel/pmap.c (pmap_unmap_page_zero): Warn that unmapping page
zero may break some BIOS functions.
| -rw-r--r-- | i386/i386at/acpi.c | 3 | ||||
| -rw-r--r-- | i386/i386at/model_dep.c | 4 | ||||
| -rw-r--r-- | i386/intel/pmap.c | 1 |
3 files changed, 8 insertions, 0 deletions
diff --git a/i386/i386at/acpi.c b/i386/i386at/acpi.c index ec8aeb1e..986b3a25 100644 --- a/i386/i386at/acpi.c +++ b/i386/i386at/acpi.c @@ -55,8 +55,11 @@ grub_machine_acpi_get_rsdpv2 (void) grub_uint8_t *ebda, *ptr; grub_dprintf ("acpi", "Looking for RSDP. Scanning EBDA\n"); + printf("ptr is %p\n", (* ((grub_uint16_t *) phystokv (0x40e))) << 4); + printf("len is %u\n", *( (grub_uint16_t *) phystokv ((* ((grub_uint16_t *) phystokv (0x40e))) << 4))); ebda = (grub_uint8_t *) phystokv ((* ((grub_uint16_t *) phystokv (0x40e))) << 4); ebda_len = * (grub_uint16_t *) ebda; + printf("EBDA len %d\n", ebda_len); if (! ebda_len) return 0; for (ptr = ebda; ptr < ebda + 0x400; ptr += 16) diff --git a/i386/i386at/model_dep.c b/i386/i386at/model_dep.c index 6093a66c..209cfb14 100644 --- a/i386/i386at/model_dep.c +++ b/i386/i386at/model_dep.c @@ -180,10 +180,14 @@ void machine_init(void) *(unsigned short *)phystokv(0x472) = 0x1234; #endif /* MACH_HYP */ +#if VM_MIN_KERNEL_ADDRESS == 0 /* * Unmap page 0 to trap NULL references. + * + * Note that this breaks accessing some BIOS areas stored there. */ pmap_unmap_page_zero(); +#endif } /* Conserve power on processor CPU. */ diff --git a/i386/intel/pmap.c b/i386/intel/pmap.c index 8a23a44d..62b33cf7 100644 --- a/i386/intel/pmap.c +++ b/i386/intel/pmap.c @@ -2835,6 +2835,7 @@ pmap_unmap_page_zero (void) { int *pte; + printf("Unmapping the zero page. Some BIOS functions may not be working any more.\n"); pte = (int *) pmap_pte (kernel_pmap, 0); if (!pte) return; |