From 07258815e96aab2c72593d0129d17051cbf68d27 Mon Sep 17 00:00:00 2001 From: Andrei Borzenkov Date: Fri, 8 May 2015 06:15:16 +0300 Subject: [PATCH] acpi: do not skip BIOS scan if EBDA length is zero EBDA layout is not standardized so we cannot assume first two bytes are length. Neither is it required by ACPI standard. HP 8710W is known to contain zeroes here. Closes: 45002 --- grub-core/commands/acpi.c | 4 ++++ grub-core/commands/i386/pc/acpi.c | 10 ++++++---- 2 files changed, 10 insertions(+), 4 deletions(-) Index: grub-2.02~beta2/grub-core/commands/acpi.c =================================================================== --- grub-2.02~beta2.orig/grub-core/commands/acpi.c +++ grub-2.02~beta2/grub-core/commands/acpi.c @@ -179,8 +179,10 @@ grub_acpi_create_ebda (void) struct grub_acpi_rsdp_v20 *v2; ebda = (grub_uint8_t *) (grub_addr_t) ((*((grub_uint16_t *)0x40e)) << 4); + grub_dprintf ("acpi", "EBDA @%p\n", ebda); if (ebda) ebda_kb_len = *(grub_uint16_t *) ebda; + grub_dprintf ("acpi", "EBDA length 0x%x\n", ebda_kb_len); if (ebda_kb_len > 16) ebda_kb_len = 0; ctx.ebda_len = (ebda_kb_len + 1) << 10; @@ -494,6 +496,8 @@ grub_cmd_acpi (struct grub_extcmd_contex if (! rsdp) rsdp = grub_machine_acpi_get_rsdpv1 (); + grub_dprintf ("acpi", "RSDP @%p\n", rsdp); + if (rsdp) { grub_uint32_t *entry_ptr; Index: grub-2.02~beta2/grub-core/commands/i386/pc/acpi.c =================================================================== --- grub-2.02~beta2.orig/grub-core/commands/i386/pc/acpi.c +++ grub-2.02~beta2/grub-core/commands/i386/pc/acpi.c @@ -29,14 +29,15 @@ grub_machine_acpi_get_rsdpv1 (void) grub_dprintf ("acpi", "Looking for RSDP. Scanning EBDA\n"); ebda = (grub_uint8_t *) ((* ((grub_uint16_t *) 0x40e)) << 4); ebda_len = * (grub_uint16_t *) ebda; - if (! ebda_len) - return 0; + if (! ebda_len) /* FIXME do we really need this check? */ + goto scan_bios; for (ptr = ebda; ptr < ebda + 0x400; ptr += 16) if (grub_memcmp (ptr, GRUB_RSDP_SIGNATURE, GRUB_RSDP_SIGNATURE_SIZE) == 0 && grub_byte_checksum (ptr, sizeof (struct grub_acpi_rsdp_v10)) == 0 && ((struct grub_acpi_rsdp_v10 *) ptr)->revision == 0) return (struct grub_acpi_rsdp_v10 *) ptr; +scan_bios: grub_dprintf ("acpi", "Looking for RSDP. Scanning BIOS\n"); for (ptr = (grub_uint8_t *) 0xe0000; ptr < (grub_uint8_t *) 0x100000; ptr += 16) @@ -56,8 +57,8 @@ grub_machine_acpi_get_rsdpv2 (void) grub_dprintf ("acpi", "Looking for RSDP. Scanning EBDA\n"); ebda = (grub_uint8_t *) ((* ((grub_uint16_t *) 0x40e)) << 4); ebda_len = * (grub_uint16_t *) ebda; - if (! ebda_len) - return 0; + if (! ebda_len) /* FIXME do we really need this check? */ + goto scan_bios; for (ptr = ebda; ptr < ebda + 0x400; ptr += 16) if (grub_memcmp (ptr, GRUB_RSDP_SIGNATURE, GRUB_RSDP_SIGNATURE_SIZE) == 0 && grub_byte_checksum (ptr, sizeof (struct grub_acpi_rsdp_v10)) == 0 @@ -67,6 +68,7 @@ grub_machine_acpi_get_rsdpv2 (void) == 0) return (struct grub_acpi_rsdp_v20 *) ptr; +scan_bios: grub_dprintf ("acpi", "Looking for RSDP. Scanning BIOS\n"); for (ptr = (grub_uint8_t *) 0xe0000; ptr < (grub_uint8_t *) 0x100000; ptr += 16)