* [Qemu-devel] [PATCH] Probe HPET existence
@ 2011-08-29 15:50 Jan Kiszka
2011-08-30 0:35 ` Kevin O'Connor
0 siblings, 1 reply; 3+ messages in thread
From: Jan Kiszka @ 2011-08-29 15:50 UTC (permalink / raw)
To: Kevin O'Connor, seabios
Cc: Andrew Theurer, Gleb Natapov, ya su, Alexander Graf, qemu-devel,
Avi Kivity
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@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
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] [PATCH] Probe HPET existence
2011-08-29 15:50 [Qemu-devel] [PATCH] Probe HPET existence Jan Kiszka
@ 2011-08-30 0:35 ` Kevin O'Connor
2011-08-31 16:45 ` Jan Kiszka
0 siblings, 1 reply; 3+ messages in thread
From: Kevin O'Connor @ 2011-08-30 0:35 UTC (permalink / raw)
To: Jan Kiszka
Cc: Andrew Theurer, Gleb Natapov, seabios, ya su, Alexander Graf,
qemu-devel, Avi Kivity
On Mon, Aug 29, 2011 at 05:50:10PM +0200, Jan Kiszka wrote:
> 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.
It looks okay to me.
BTW, any particular reason to use 0x05F5E100 instead of 100000000?
-Kevin
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] [PATCH] Probe HPET existence
2011-08-30 0:35 ` Kevin O'Connor
@ 2011-08-31 16:45 ` Jan Kiszka
0 siblings, 0 replies; 3+ messages in thread
From: Jan Kiszka @ 2011-08-31 16:45 UTC (permalink / raw)
To: Kevin O'Connor
Cc: Andrew Theurer, Gleb Natapov, seabios, ya su, Alexander Graf,
qemu-devel, Avi Kivity
On 2011-08-30 02:35, Kevin O'Connor wrote:
> On Mon, Aug 29, 2011 at 05:50:10PM +0200, Jan Kiszka wrote:
>> 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.
>
> It looks okay to me.
>
> BTW, any particular reason to use 0x05F5E100 instead of 100000000?
No, I just blindly grabbed the first number I found in the spec. You may
change if you like on commit.
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2011-08-31 16:46 UTC | newest]
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2011-08-29 15:50 [Qemu-devel] [PATCH] Probe HPET existence Jan Kiszka
2011-08-30 0:35 ` Kevin O'Connor
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