Before safecopies, the IO_ENDPT and DL_ENDPT message fields were needed
to know which actual process to copy data from/to, as that process may
not always be the caller. Now that we have full safecopy support, these
fields have become useless for that purpose: the owner of the grant is
*always* the caller. Allowing the caller to supply another endpoint is
in fact dangerous, because the callee may then end up using a grant
from a third party. One could call this a variant of the confused
deputy problem.
From now on, safecopy calls should always use the caller's endpoint as
grant owner. This fully obsoletes the DL_ENDPT field in the
inet/ethernet protocol. IO_ENDPT has other uses besides identifying the
grant owner though. This patch renames IO_ENDPT to USER_ENDPT, not only
because that is a more fitting name (it should never be used for I/O
after all), but also in order to intentionally break any old system
source code outside the base system. If this patch breaks your code,
fixing it is fairly simple:
- DL_ENDPT should be replaced with m_source;
- IO_ENDPT should be replaced with m_source when used for safecopies;
- IO_ENDPT should be replaced with USER_ENDPT for any other use, e.g.
when setting REP_ENDPT, matching requests in CANCEL calls, getting
DEV_SELECT flags, and retrieving of the real user process's endpoint
in DEV_OPEN.
The changes in this patch are binary backward compatible.
completed (successfully or not). AMF_NOTIFY_ERR can be used if the sender
only wishes to be notified in case of an error (e.g., EDEADSRCDST). A new
endpoint ASYNCM will be the sender of the notification.
. helps debugging output; you can see the difference
between parent and child easily (it's sometimes
confusing to see an expected endpoint number with
an unexpected name, i.e. before exec())
. when processes crash after fork and before exec, it's
an instant hint that that's what's going on, instead of
it being the parent (endpoint numbers don't usually convey
this)
. name returns to 'normal' after exec(), so *F isn't visible
normally at all. (Except for for RS which forks apparently.)
Headers that will be shared between old includes and NetBSD-like includes
are moved into common/include tree. They are still copied in /usr/include
in 'make includes', so compilation and programs aren't be affected.
- kernel maintains a cpu_info array which contains various
information about each cpu as filled when each cpu boots
- the information contains idetification, features etc.
- flush TLB of processes only if the page tables has been changed and
the page tables of this process are already loaded on this cpu which
means that there might be stale entries in TLB. Until now SMP was
always flushing TLB to make sure everything is consistent.
- accidentaly this wasn't part of the SMP merge and the implementation
remained uncomplete with the timer keeping ticking periodically
- APIC timer is set for a signel shot and restarted everytime it
expires. This way we can keep the AP's trully idle
- the timer is restarted a little later before leaving to userspace
- LAPIC_TIMER_ICR is written before LAPIC_LVTTR so the newest value is
used
- fixed spurious and error interrupt handlers
- not to hog the system the warning isn't reported every time, just
once every 100 times, similarly for the spurious PIC interrupts
- a different set of MSRs and performance counters is used on AMD
- when initializing NMI watchdog the test for Intel architecture
performance counters feature only applies to Intel now
- NMI is enabled if the CPU belongs to a family which has the
performance counters that we use
- sometimes the system needs to know precisely on what type of cpu is
running. The cpu type id detected during arch specific
initialization and kept in the machine structure for later use.
- as a side-effect the information is exported to userland
- the Intel architecture cycle counter (performance counter) does not
count when the CPU is idle therefore we use busy loop instead of
halting the cpu when there is nothing to schedule
- the downside is that handling interrupts may be accounted as idle
time if a sample is taken before we get out of the nested trap and
pick a new process
- when profiling is compiled in kernel includes a 64M buffer for
sample
- 64M is the default used by profile tool as its buffer
- when using nmi profiling it is not possible to always copy sample
stright to userland as the nmi may (and does) happen in bad moments
- reduces sampling overhead as samples are copied out only when
profiling stops
- if profile --nmi kernel uses NMI watchdog based sampling based on
Intel architecture performance counters
- using NMI makes kernel profiling possible
- watchdog kernel lockup detection is disabled while sampling as we
may get unpredictable interrupts in kernel and thus possibly many
false positives
- if watchdog is not enabled at boot time, profiling enables it and
turns it of again when done
- when kernel profiles a process for the first time it saves an entry
describing the process [endpoint|name]
- every profile sample is only [endpoint|pc]
- profile utility creates a table of endpoint <-> name relations and
translates endpoints of samples into names and writing out the
results to comply with the processing tools
- "task" endpoints like KERNEL are negative thus we must cast it to
unsigned when hashing
