[SeaBIOS] [PATCH] Probe HPET existence
Jan Kiszka
jan.kiszka at siemens.com
Mon Aug 29 17:50:10 CEST 2011
QEMU does not provide a HPET block if it was configured with -no-hpet,
other machines SeaBIOS runs on may lack a HPET as well. Perform basic
checks the ID register for a reasonable vendor ID and a clock period
within the valid range, do not build the HPET table if that fails.
Signed-off-by: Jan Kiszka <jan.kiszka at siemens.com>
---
This allows to postpone the hpet_fw_cfg vs. ACPI discussion until we
have >1 HPET blocks and/or put them at non-standard addresses.
src/acpi.c | 14 +++++++++++++-
1 files changed, 13 insertions(+), 1 deletions(-)
diff --git a/src/acpi.c b/src/acpi.c
index ea7b171..29160f4 100644
--- a/src/acpi.c
+++ b/src/acpi.c
@@ -158,6 +158,9 @@ struct acpi_20_hpet {
} PACKED;
#define ACPI_HPET_ADDRESS 0xFED00000UL
+#define HPET_ID 0x000
+#define HPET_PERIOD 0x004
+
/*
* SRAT (NUMA topology description) table
*/
@@ -464,7 +467,16 @@ build_ssdt(void)
static void*
build_hpet(void)
{
- struct acpi_20_hpet *hpet = malloc_high(sizeof(*hpet));
+ struct acpi_20_hpet *hpet;
+ const void *hpet_base = (void *)ACPI_HPET_ADDRESS;
+ u32 hpet_vendor = readl(hpet_base + HPET_ID) >> 16;
+ u32 hpet_period = readl(hpet_base + HPET_PERIOD);
+
+ if (hpet_vendor == 0 || hpet_vendor == 0xffff ||
+ hpet_period == 0 || hpet_period > 0x05F5E100)
+ return NULL;
+
+ hpet = malloc_high(sizeof(*hpet));
if (!hpet) {
warn_noalloc();
return NULL;
--
1.7.3.4
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