[9fans] cache question

[9fans] cache question

[Tim Newsham]

Hi,
    I'm seeing a bug where I get some random crashes when I boot
my kernel with the dcache on which go away if I turn off the
dcache.  I'm guessing this means that something in the cache
needs to get flushed that isnt.  What it is or when I should
flush is less clear to me.  The portable code lets the machine
specific code know when it should perform an instruction cache
flush, but never indicates any data flushes.

The cache is virtually addressed and physically tagged.  Its
twice as big as a VM page size, and I have pgcolor defined
to return ((va>>PGSHIFT) & 1).

Any pointers would be appreciated,
Tim N.

Re: [9fans] cache question

[Tim Newsham]

>   I'm seeing a bug where I get some random crashes when I boot
> my kernel with the dcache on which go away if I turn off the
> dcache.  I'm guessing this means that something in the cache
> needs to get flushed that isnt.  What it is or when I should
> flush is less clear to me.  The portable code lets the machine
> specific code know when it should perform an instruction cache
> flush, but never indicates any data flushes.

The closest thing I've found to a solution so far is to flush
a page from the dcache in putmmu() every time a page is added.
This seems a bit excessive (compare with icache which is only
flushed when PG_TXTFLUSH is indicated).

Tim N.