IA-PC HPET IA-PC HPET (High Precision Event Timer) is a specification which was jointly developed by Intel and Microsoft in the early part of this decade.. (High Precision Event Timer) är en specifikation som utvecklats gemensamt av Intel och Microsoft i början av detta årtionde .. The latest version is dated October 2004. Den senaste versionen är daterad oktober 2004. It's stated purpose is to Det uttalade syftet är att
initially supplement and eventually replace the legacy 8254 Programmable Interval Timer and the Real Time Clock Periodic Interrupt generation functions that are currently used as the 'de-facto' timer hardware for IA-PCs. först komplettera och så småningom ersätta de gamla 8.254 programmerbara intervalltimer och realtidsklockan Periodic Interrupt funktioner generation som används för närvarande som "de-facto" timer hårdvara för IA-datorer.
The Den HPET HPET architecture defines a set of timers that can be used by the operating system. Arkitekturen definierar ett antal timers som kan användas av operativsystemet. A timer block is a combination of a single counter and up to 32 comparators and match registers. En timer block är en kombination av en enda disk och upp till 32 jämförelsepreparaten och matcha register. The comparator compares the contents of the match register against the value of a free running monotonic up-counter. Referensanläggningen jämför innehållet i matchen register mot värdet av en lösspringande monoton upp-disk. When the output of the up-counter equals the value in the match register an interrupt is generated. När produktionen av upp-disk motsvarar värdet i matchen registrera ett avbrott genereras. Each of the comparators can output an interrupt. Varje komparator kan mata ett avbrott. A maximum of 8 timer blocks are supported for a total of 256 timers. Högst 8 timer block finns stöd för totalt 256 timers. Each timer block can have different clocking attributes. Varje timer block kan ha olika klockning attribut. Specific implementations may include only a subset of these timers. Särskilda implementeringar kan omfatta endast en delmängd av dessa timers. A minimum of three timers is required. Minst tre timers krävs.
The specification contains the following block diagram of the HPET architecture. Specifikationen innehåller följande blockschema av HPET arkitektur.
Some of the timers may be enabled to generate a periodic interrupt. Vissa timers kan ges möjlighet att skapa en återkommande avbrott. If a timer is set to be periodic, its period is added to the match register each time a match occurs, thus computing the next time for this timer to generate an interrupt.. Om timern är inställd på att med jämna mellanrum så att giltighetstiden skall läggas till matchen registrera varje gång en match inträffar, alltså datorer nästa gång för denna timer för att generera ett avbrott .. An up-counter is usually 64 bits wide but 32-bit implementations are permitted by the specification and 64-bit up-counters can also be driven in 32-bit mode. En upp-counter är vanligen 64 bitar bred men 32-bitars implementeringar är tillåtet enligt specifikationen och 64-bit upp-diskar kan även köras i 32-bitars läge. Up-counters run at a minimum of 10 MHz. Up-räknare köras minst 10 MHz. which is much faster than the older vilket är mycket snabbare än de äldre RTC RTC (Real Time Clock) and can thus produce periodic interrupts at a much higher resolution. (Real Time Clock) och kan därmed producera regelbundna avbrott på en mycket högre upplösning. The registers associated with these timers are mapped to memory space. De register i samband med dessa timers mappas till minnesutrymme.
The BIOS uses BIOS använder ACPI ACPI ( Advanced Configuration and Power Interface) functionality to inform the operating system of the location of the HPET memory-mapped register space. (Advanced Configuration and Power Interface) funktionalitet för att informera operativsystem lokaliseringen av HPET minne-kartläggs register utrymme. Here is an example of a disassembled ACPI HPET table from an Intel DX48BT2 (AKA BoneTrail) motherboard. Här är ett exempel på en nedmonterad ACPI HPET bord från en Intel DX48BT2 (AKA BoneTrail) moderkort.
$ cat /sys/firmware/acpi/tables/HPET > /var/tmp/hpet.out $ iasl -d /var/tmp/hpet.out $ cat /var/tmp/hpet.dsl /* * Intel ACPI Component Architecture * AML Disassembler version 20090123 * * Disassembly of /var/tmp/hpet.out, Sun Jul 5 19:34:47 2009 * * ACPI Data Table [HPET] * * Format: [HexOffset DecimalOffset ByteLength] FieldName : FieldValue */ [000h 000 4] Signature : "HPET" /* High Precision Event Timer table */ [004h 004 4] Table Length : 00000038 [008h 008 1] Revision : 01 [009h 009 1] Checksum : CE [00Ah 010 6] Oem ID : "INTEL " [010h 016 8] Oem Table ID : "DX48BT2 " [018h 024 4] Oem Revision : 0000076E [01Ch 028 4] Asl Compiler ID : "MSFT" [020h 032 4] Asl Compiler Revision : 01000013 [024h 036 4] Hardware Block ID : 8086A301 [028h 040 12] Timer Block Register :[028h 040 1] Space ID : 00 (SystemMemory) [029h 041 1] Bit Width : 00 [02Ah 042 1] Bit Offset : 00 [02Bh 043 1] Access Width : 00 [02Ch 044 8] Address : 00000000FED00000 [034h 052 1] Sequence Number : 00 [035h 053 2] Minimum Clock Ticks : 0001 [037h 055 1] Flags (decoded below) : 00 Page Protect : 0 4K Page Protect : 0 64K Page Protect : 0 Raw Table Data 0000: 48 50 45 54 38 00 00 00 01 CE 49 4E 54 45 4C 20 HPET8.....INTEL 0010: 44 58 34 38 42 54 32 20 6E 07 00 00 4D 53 46 54 DX48BT2 n...MSFT 0020: 13 00 00 01 01 A3 86 80 00 00 00 00 00 00 D0 FE ................ 0030: 00 00 00 00 00 01 00 00 ........ $
See page 30 of the HPET v1.0a specification for a detailed breakdown of the individual bits in the Event Time Block (called Hardware Block by the AML disassember). Se sidan 30 i HPET v1.0a specifikationen för en detaljerad uppdelning av de enskilda bitar i tiden för händelsen Block (kallas Hardware Block av AML disassember). Note that only one Event Timer Block need be described in the HPET table in order to bootstrap an operating system. Observera att endast en händelse Timer Block behöver beskrivas i HPET bordet för att starta ett operativsystem. This is the case here. Detta är fallet här. For non-legacy platforms, the Event Timer Block described in the HPET is the one that provides functionality to replace the 8254/RTC Periodic Interrupt Logic. För icke-legacy plattformar, beskrev Event Timer Block i HPET är den som ger funktionalitet för att ersätta den 8254/RTC Periodic Interrupt Logic.
Other Event Time Blocks are described in the ACPI namespace. Annan händelse Time Block beskrivs i ACPI namnrymden. Here is the relevant section from the disassembled ACPI DSDT table. Här är det relevanta avsnittet från de demonterade ACPI DSDT bord.
Device (HPET)
{
Name (_HID, EisaId ("PNP0103"))
Name (_CRS, ResourceTemplate ()
{
Memory32Fixed (ReadOnly,
0xFED00000, // Address Base
0x00004000, // Address Length
)
})
Method (_STA, 0, NotSerialized)
{
If (HPEE)
{
Return (0x0F)
}
Else
{
Return (Zero)
}
}
}
Note the assigned PNPID ( PNP0103 ) for the HPET. Observera tilldelade PNPID (PNP0103) för HPET. Because no _UID is specified it means that there are no other HPET timer blocks. Eftersom ingen _UID anges betyder det att det inte finns några andra HPET timer block.
Here is a list of the HPET-related messages outputted when this particular motherboard is booted up under Fedora 11. Här är en lista över HPET-relaterade outputted meddelanden när detta moderkort startas upp under Fedora 11.
$ dmesg | grep -i HPET ACPI: HPET CFBF2000, 0038 (r1 INTEL DX48BT2 76E MSFT 1000013) ACPI: HPET id: 0x8086a301 base: 0xfed00000 hpet clockevent registered HPET: 4 timers in total, 0 timers will be used for per-cpu timer hpet0: at MMIO 0xfed00000, IRQs 2, 8, 0, 0 hpet0: 4 comparators, 64-bit 14.318180 MHz counter rtc0: alarms up to one month, 114 bytes nvram, hpet irqs $
The first line is outputted when the ACPI HPET table is read. Den första raden är outputted när ACPI HPET tabellen läses. The second line is outputted when the ACPI HPET table is mapped into memory by …/arch/x86/kernel/acpi/boot.c . Den andra raden är outputted när ACPI HPET tabellen mappas till minnet av ... / arch/x86/kernel/acpi/boot.c. The next line is outputted when the HPET legacy interrupts are started and HPET is registered as the global clock. Nästa rad är outputted när HPET arvet avbryter startas och HPET är registrerad som global clock. The following line is outputted when the kernel checks to ensure that at least one timer is reserved for userspace ( /dev/hpet .) The next two lines of output comes from the HPET device driver ( …/drivers/char/hpet.c .) It shows that 2 timers have allocated interrupts and two do not.. Följande rad är outputted när kärnan kontrollera att åtminstone en timer är reserverad för userspace (/ dev / hpet.) Nästa två rader av produktionen kommer från HPET drivrutinen (... / drivers / char / hpet.c. ) Det visar att 2 timers har anslagit avbrott och två inte ..
Here is the relevant part of the output from /proc/time_list as it relates to HPET: Här är den aktuella delen av produktionen från / proc / time_list det rör HPET:
Tick Device: mode: 1 Broadcast device Clock Event Device: hpet max_delta_ns: 149983005959 min_delta_ns: 5000 mult: 61496114 shift: 32 mode: 3 next_event: 9223372036854775807 nsecs set_next_event: hpet_legacy_next_event set_mode: hpet_legacy_set_mode event_handler: tick_handle_oneshot_broadcast tick_broadcast_mask: 00000000 tick_broadcast_oneshot_mask: 00000000
Here is the output from /proc/sys/dev/hpet and /proc/driver/rtc : Här är resultaten från / proc / sys / dev / hpet och / proc / driver / RTC:
$ cat /proc/sys/dev/hpet/max-user-freq 64 $ cat /proc/driver/rtc rtc_time : 06:34:31 rtc_date : 2009-07-06 alrm_time : **:24:40 alrm_date : ****-**-** alarm_IRQ : no alrm_pending : no 24hr : yes periodic_IRQ : no update_IRQ : no HPET_emulated : yes DST_enable : no periodic_freq : 1024 batt_status : okay
The HPET driver ( /dev/hpet ) has a similar API to the Real Time Clock driver. Den HPET drivrutin (/ dev / hpet) har en liknande API till Real Time Clock Driver. It is a character device which can support any number of HPET devices. Det är ett tecken anordning som kan stödja en rad HPET enheter. The kernel API has three interfaces exported from the driver: Kärnan API har tre gränssnitt som exporteras från föraren:
hpet_register( struct hpet_task *tp, int periodic ) hpet_unregister( struct hpet_task *tp ) hpet_control( struct hpet_task *tp, unsigned int cmd, unsigned long arg )
The userspace interface to HPET is defined in the header /usr/include/linux/hpet.h . Den userspace gränssnitt till HPET definieras i sidhuvudet / usr / include / linux / hpet.h. The current set of supported operations is: Den nuvarande uppsättningen stöds verksamheten är:
#define HPET_IE_ON _IO('h', 0x01) /* interrupt on */
#define HPET_IE_OFF _IO('h', 0x02) /* interrupt off */
#define HPET_INFO _IOR('h', 0x03, struct hpet_info) /* get information */
#define HPET_EPI _IO('h', 0x04) /* enable periodic */
#define HPET_DPI _IO('h', 0x05) /* disable periodic */
#define HPET_IRQFREQ _IOW('h', 0x6, unsigned long) /* set frequency */
The following example shows how to use the published interface to access a HPET and call a simple periodic signal handler hpet_alarm between 2 and 99 times a second. Följande exempel visar hur du använder publicerade gränssnitt få tillgång till en HPET och kräver en enkel periodisk hpet_alarm signal handler mellan 2 och 99 gånger per sekund.
#include <stdio.h>
#include <stdlib.h;>
#include <fcntl.h>
#include <time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>
#include <fcntl.h>
#include <sys/time.h>
#include <linux/hpet.h>
#include <stdint.h>
#include <sys/ioctl.h>
#include <signal.h>
static uint16_t hpet_sigio_count;
static uint64_t secs;
static void
hpet_alarm(int val)
{
struct timespec t;
clock_gettime(CLOCK_REALTIME, &t);
if (!secs) secs = t.tv_sec;
fprintf(stderr, "hpet_alarm called. iteration: %2d secs: %ld nsecs: %ld \n",
hpet_sigio_count, (t.tv_sec - secs) , t.tv_sec * 100000 + t.tv_nsec );
hpet_sigio_count++;
}
int
main(int argc, const char **argv)
{
struct sigaction old, new;
struct hpet_info info;
int frequency;
int iterations;
int retval = 0;
int fd;
int r, i, value;
if (argc != 3) {
fprintf(stderr, "Usage: %s frequency(1-64) iterations(10-99)\n", argv[0]);
return -1;
}
frequency = atoi(argv[1]);
iterations = atoi(argv[2]);
if (frequency > 64 || frequency < 1 ) {
fprintf(stderr, "ERROR: Invalid value for frequency\n");
return -1;
}
if (iterations < 10 || iterations > 99 ) {
fprintf(stderr, "ERROR: Invalid value for iterations\n");
return -1;
}
hpet_sigio_count = 0;
sigemptyset(&new.sa_mask);
new.sa_flags = 0;
new.sa_handler = hpet_alarm;
sigaction(SIGIO, NULL, &old);
sigaction(SIGIO, &new, NULL);
fd = open("/dev/hpet", O_RDONLY);
if (fd < 0) {
fprintf(stderr, "ERROR: Failed to open /dev/hpet\n");
return -1;
}
if ((fcntl(fd, F_SETOWN, getpid()) == 1) ||
((value = fcntl(fd, F_GETFL)) == 1) ||
(fcntl(fd, F_SETFL, value | O_ASYNC) == 1)) {
fprintf(stderr, "ERROR: fcntl failed\n");
retval = 1;
goto fail;
}
if (ioctl(fd, HPET_IRQFREQ, frequency) < 0) {
fprintf(stderr, "ERROR: Could not set /dev/hpet to have a %2dHz timer\n", frequency);
retval = 2;
goto fail;
}
if (ioctl(fd, HPET_INFO, &info) < 0) {
fprintf(stderr, "ERROR: failed to get info\n");
retval = 3;
goto fail;
}
fprintf(stdout, "\nhi_ireqfreq: 0x%lx hi_flags: %0x%lx hi_hpet: 0x%x hi_timer: 0x%x\n\n",
info.hi_ireqfreq, info.hi_flags, info.hi_hpet, info.hi_timer);
r = ioctl(fd, HPET_EPI, 0);
if (info.hi_flags && (r < 0)) {
fprintf(stderr, "ERROR: HPET_EPI failed\n");
retval = 4;
goto fail;
}
if (ioctl(fd, HPET_IE_ON, 0) < 0) {
fprintf(stderr, "ERROR: HPET_IE_ON failed\n");
retval = 5;
goto fail;
}
/* wait for specified number of signal interrupts */
for (i = 0; i < iterations; i++) {
(void) pause();
}
if (ioctl(fd, HPET_IE_OFF, 0) < 0) {
fprintf(stderr, "ERROR: HPET_IE_OFF failed\n");
retval = 6;
}
fail:
sigaction(SIGIO, &old, NULL);
if (fd > 0)
close(fd);
return retval;
}
Here is the output from this example when it is invoked with a frequency of 32 and an iteration count of 64. Här är resultaten från detta exempel vid aktivering med en frekvens på 32 och en iteration räkna till 64.
$ sudo ./hpet_example 32 64 hi_ireqfreq: 0x20 hi_flags: 00 hi_hpet: 0x2 hi_timer: 0x4a1cb9c8 hpet_alarm called. iteration: 0 secs: 0 nsecs: 124683205055050 hpet_alarm called. iteration: 1 secs: 0 nsecs: 124683236313149 hpet_alarm called. iteration: 2 secs: 0 nsecs: 124683267566342 hpet_alarm called. iteration: 3 secs: 0 nsecs: 124683298821905 hpet_alarm called. iteration: 4 secs: 0 nsecs: 124683330077493 hpet_alarm called. iteration: 5 secs: 0 nsecs: 124683361341893 hpet_alarm called. iteration: 6 secs: 0 nsecs: 124683392590764 hpet_alarm called. iteration: 7 secs: 0 nsecs: 124683423849157 hpet_alarm called. iteration: 8 secs: 0 nsecs: 124683455101917 hpet_alarm called. iteration: 9 secs: 0 nsecs: 124683486357683 hpet_alarm called. iteration: 10 secs: 0 nsecs: 124683517617931 hpet_alarm called. iteration: 11 secs: 0 nsecs: 124683548872198 hpet_alarm called. iteration: 12 secs: 1 nsecs: 124682580229541 hpet_alarm called. iteration: 13 secs: 1 nsecs: 124682611481235 hpet_alarm called. iteration: 14 secs: 1 nsecs: 124682642740016 hpet_alarm called. iteration: 15 secs: 1 nsecs: 124682673992697 hpet_alarm called. iteration: 16 secs: 1 nsecs: 124682705247479 hpet_alarm called. iteration: 17 secs: 1 nsecs: 124682736504664 hpet_alarm called. iteration: 18 secs: 1 nsecs: 124682767758840 hpet_alarm called. iteration: 19 secs: 1 nsecs: 124682799014280 hpet_alarm called. iteration: 20 secs: 1 nsecs: 124682830270129 hpet_alarm called. iteration: 21 secs: 1 nsecs: 124682861530334 hpet_alarm called. iteration: 22 secs: 1 nsecs: 124682892784577 hpet_alarm called. iteration: 23 secs: 1 nsecs: 124682924038220 hpet_alarm called. iteration: 24 secs: 1 nsecs: 124682955294110 hpet_alarm called. iteration: 25 secs: 1 nsecs: 124682986550572 hpet_alarm called. iteration: 26 secs: 1 nsecs: 124683017805756 hpet_alarm called. iteration: 27 secs: 1 nsecs: 124683049061117 hpet_alarm called. iteration: 28 secs: 1 nsecs: 124683080318331 hpet_alarm called. iteration: 29 secs: 1 nsecs: 124683111576954 hpet_alarm called. iteration: 30 secs: 1 nsecs: 124683142828988 hpet_alarm called. iteration: 31 secs: 1 nsecs: 124683174083954 hpet_alarm called. iteration: 32 secs: 1 nsecs: 124683205337967 hpet_alarm called. iteration: 33 secs: 1 nsecs: 124683236593144 hpet_alarm called. iteration: 34 secs: 1 nsecs: 124683267851530 hpet_alarm called. iteration: 35 secs: 1 nsecs: 124683299104054 hpet_alarm called. iteration: 36 secs: 1 nsecs: 124683330358748 hpet_alarm called. iteration: 37 secs: 1 nsecs: 124683361617445 hpet_alarm called. iteration: 38 secs: 1 nsecs: 124683392870249 hpet_alarm called. iteration: 39 secs: 1 nsecs: 124683424124489 hpet_alarm called. iteration: 40 secs: 1 nsecs: 124683455379717 hpet_alarm called. iteration: 41 secs: 1 nsecs: 124683486634424 hpet_alarm called. iteration: 42 secs: 1 nsecs: 124683517889149 hpet_alarm called. iteration: 43 secs: 1 nsecs: 124683549144315 hpet_alarm called. iteration: 44 secs: 2 nsecs: 124682580500695 hpet_alarm called. iteration: 45 secs: 2 nsecs: 124682611761325 hpet_alarm called. iteration: 46 secs: 2 nsecs: 124682643011863 hpet_alarm called. iteration: 47 secs: 2 nsecs: 124682674265864 hpet_alarm called. iteration: 48 secs: 2 nsecs: 124682705521034 hpet_alarm called. iteration: 49 secs: 2 nsecs: 124682736776049 hpet_alarm called. iteration: 50 secs: 2 nsecs: 124682768030654 hpet_alarm called. iteration: 51 secs: 2 nsecs: 124682799285398 hpet_alarm called. iteration: 52 secs: 2 nsecs: 124682830544701 hpet_alarm called. iteration: 53 secs: 2 nsecs: 124682861797319 hpet_alarm called. iteration: 54 secs: 2 nsecs: 124682893051578 hpet_alarm called. iteration: 55 secs: 2 nsecs: 124682924306748 hpet_alarm called. iteration: 56 secs: 2 nsecs: 124682955562132 hpet_alarm called. iteration: 57 secs: 2 nsecs: 124682986823545 hpet_alarm called. iteration: 58 secs: 2 nsecs: 124683018073636 hpet_alarm called. iteration: 59 secs: 2 nsecs: 124683049327560 hpet_alarm called. iteration: 60 secs: 2 nsecs: 124683080586707 hpet_alarm called. iteration: 61 secs: 2 nsecs: 124683111841132 hpet_alarm called. iteration: 62 secs: 2 nsecs: 124683143095147 hpet_alarm called. iteration: 63 secs: 2 nsecs: 124683174349985 hpet_alarm called. iteration: 64 secs: 2 nsecs: 124683205607103 $
Well, I think that I have provided you with enough information so that you should now be able to go away and experiment with the HPET interface yourself. Tja, jag tror att jag har gett dig tillräckligt med information så att du nu ska kunna gå iväg och experimentera med HPET gränssnittet själv.
By the way, not all VMware products support HPET. Förresten, inte alla VMware produkter stöd HPET. Currently ESX does not provide a virtual HPET to guest operating systems and in some cases it may be necessary to disable HPET altogether because of timer drift in virtual machines. För närvarande ESX är inte ett virtuellt HPET att gästoperativsystem och i vissa fall kan det vara nödvändigt att inaktivera HPET helt och hållet på grund av timer drift i virtuella maskiner. See Se VMware TimeKeeping VMware Tidtagning for more information. för mer information.
PS I tested the the above example on an Intel DX48BT2 motherboard running a 2.6.29.5-191 kernel. PS Jag har testat ovanstående exempel på en Intel DX48BT2 moderkort kör en 2.6.29.5-191 kärna.
