purely as an aside
this detailed conversation on how notes are handled in the
kernel is very interesting, I was trying to understand this myself
recently and gave up; I will now try again.
Thanks,
-Steve
I'm not claiming anyone to be wrong. I want to solve
this problem.
i'm not sure there is a problem with notes. but i really can't
answer that question. someone with a better understanding
of what notes are supposed to be could answer this.
I also noted that i think this is the correct
I'm not claiming anyone to be wrong. I want to solve
this problem.
i'm not sure there is a problem with notes. but i really can't
answer that question. someone with a better understanding
of what notes are supposed to be could answer this.
I also noted that i think this is the
erik quanstrom wrote:
it would also be interesting to know if you are
seeing this randomly or if you can reliable reproduce
this condition.
i can reproduce it with this:
http://cm.bell-labs.com/sources/contrib/cinap_lenrek/traptest/
8c test.c
8a int80.s
8l test.8 int80.8
./8.out
8.out
Kernel Panic wrote:
http://cm.bell-labs.com/sources/contrib/cinap_lenrek/traptest/
8c test.c
8a int80.s
8l test.8 int80.8
./8.out
8.out 12490667: suicide: sys: trap: general protection violation
pc=0x1333
the parent process loops and does fake syscalls while
the child posts notes to it.
i can reproduce it with this:
http://cm.bell-labs.com/sources/contrib/cinap_lenrek/traptest/
8c test.c
8a int80.s
8l test.8 int80.8
./8.out
8.out 12490667: suicide: sys: trap: general protection violation
pc=0x1333
okay. it seems pretty clear from the code that you're dead
No! Notes are bufferd in the up-note[] array. If you are in the note handler,
another process *can* send you further (NUser) notes without doing any harm.
If we are in the note handler (up-notified == 1) and notify() gets hit,
it will do nothing and return 0 see:
/sys/src/9/pc/trap.c:
i think you may be misunderstanding what i'm saying.
the test for n-flag does not appear to be accidental.
i am not quite sure why that test is there, but i go on
the assumption that presotto knew what he was doing.
if you're going to claim he was wrong, i think you'd better
have good
I run into an interesting problem with linuxemu.
The problem *seems* to be that traps can be
enqueued in the process note array *after* some
other note causing notify() to kill us.
Please correct me if i miss(understand) something
here. It just hit my mind after hours of late night
debugging.
it looks like you get the second trap while
you are still in your notify handler, since
i think this test
(up-notified || up-notify==0)
is for a proc in a notify handler getting a system
trap (or a proc with no notify handler).
it would be very interesting to know what the system
trap is.
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