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feat(hal-x86_64): more local APIC embetterments #505

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hawkw wants to merge 5 commits into main from eliza/lapic-oneshot

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hawkw commented Jan 5, 2025

No description provided.

hawkw added a commit that referenced this pull request


          fix(hal-x86_64): don't clobber reserved LVT_TIMER bits (#505)

4ec96ff

Currently, we set wholly new values for the `LVT_TIMER` register,
clobbering whatever's in the reserved parts of the bitfield. Let's
update it in place, instead.

In practice, zeroing the reserved bits doesn't *seem* to cause any
problems, but it seems good to not do anyway...

hawkw added a commit that referenced this pull request


          feat(hal-x86_64): store LAPIC timer calibration (#505)

4721eab

This way, we don't re-calibrate every time we call
`start_periodic_timer`. This will also be used when adding the one-shot
timer mode (see #498).

hawkw added a commit that referenced this pull request


          feat(hal-x86_64): avg multiple PIT LAPIC calibrations (#505)

This commit changes the code for calibrating the local APIC timer
frequency using the PIT do multiple PIT sleeps and average the delta
across them. This should maybe make the PIT calibration mechanism more
resilient to random noise? Eventually, we can also check if an attempt
is way outside the expected range and throw it out.

hawkw added a commit that referenced this pull request


          feat(hal-x86_64): add LocalApic::interrupt_in (#505)

fbe0e96

This is a rudimentary first pass on #498 adding a method to `LocalApic`
to trigger a single oneshot timer interrupt after a given duration. It
would be nice to also have a full-on blocking sleep method, like we do
for the PIT.

hawkw force-pushed the eliza/lapic-oneshot branch from 3fc89ca to fbe0e96 Compare

January 5, 2025 18:42

hawkw added a commit that referenced this pull request


          feat(hal-x86_64): add LocalApic::version (#505)

c52d266

The local APIC has a `VERSION` register that tells you...the version, as
well as some other useful information like the number of LVT entries.
Let's add a method to read this register.

hawkw added a commit that referenced this pull request


          fix(hal-x86_64): don't clobber reserved LVT_TIMER bits (#505)

696f26a

Currently, we set wholly new values for the `LVT_TIMER` register,
clobbering whatever's in the reserved parts of the bitfield. Let's
update it in place, instead.

In practice, zeroing the reserved bits doesn't *seem* to cause any
problems, but it seems good to not do anyway...

hawkw added a commit that referenced this pull request


          feat(hal-x86_64): store LAPIC timer calibration (#505)

b3f700d

This way, we don't re-calibrate every time we call
`start_periodic_timer`. This will also be used when adding the one-shot
timer mode (see #498).

hawkw added a commit that referenced this pull request


          feat(hal-x86_64): avg multiple PIT LAPIC calibrations (#505)

c617db4

This commit changes the code for calibrating the local APIC timer
frequency using the PIT do multiple PIT sleeps and average the delta
across them. This should maybe make the PIT calibration mechanism more
resilient to random noise? Eventually, we can also check if an attempt
is way outside the expected range and throw it out.

hawkw force-pushed the eliza/lapic-oneshot branch from fbe0e96 to 3a02417 Compare

January 5, 2025 18:43

hawkw added a commit that referenced this pull request


          feat(hal-x86_64): add LocalApic::interrupt_in (#505)

3a02417

This is a rudimentary first pass on #498 adding a method to `LocalApic`
to trigger a single oneshot timer interrupt after a given duration. It
would be nice to also have a full-on blocking sleep method, like we do
for the PIT.

hawkw added 5 commits

January 5, 2025 11:23


          feat(hal-x86_64): add LocalApic::version (#505)

f736a10

The local APIC has a `VERSION` register that tells you...the version, as
well as some other useful information like the number of LVT entries.
Let's add a method to read this register.


          fix(hal-x86_64): don't clobber reserved LVT_TIMER bits (#505)

Currently, we set wholly new values for the `LVT_TIMER` register,
clobbering whatever's in the reserved parts of the bitfield. Let's
update it in place, instead.

In practice, zeroing the reserved bits doesn't *seem* to cause any
problems, but it seems good to not do anyway...


          feat(hal-x86_64): store LAPIC timer calibration (#505)

cdb5257

This way, we don't re-calibrate every time we call
`start_periodic_timer`. This will also be used when adding the one-shot
timer mode (see #498).


          feat(hal-x86_64): avg multiple PIT LAPIC calibrations (#505)

e8554b9

This commit changes the code for calibrating the local APIC timer
frequency using the PIT do multiple PIT sleeps and average the delta
across them. This should maybe make the PIT calibration mechanism more
resilient to random noise? Eventually, we can also check if an attempt
is way outside the expected range and throw it out.


          feat(hal-x86_64): add LocalApic::interrupt_in (#505)

3f367f8

This is a rudimentary first pass on #498 adding a method to `LocalApic`
to trigger a single oneshot timer interrupt after a given duration. It
would be nice to also have a full-on blocking sleep method, like we do
for the PIT.

hawkw force-pushed the eliza/lapic-oneshot branch from 3a02417 to 3f367f8 Compare

January 5, 2025 19:37

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