On Mon, 21 Mar 2022, Peter Maydell wrote:
On Mon, 21 Mar 2022 at 10:31, Thomas Huth <th...@redhat.com> wrote:
FYI, I'm seeing a memory leak in via_isa_realize() when building
QEMU with sanitizers enabled or when running QEMU through valgrind:
Same problem happens with qemu-system-ppc64 and the pegasos2 machine.
No clue how to properly fix this... is it safe to free the pointer
at the end of the function?
This is because the code is still using the old function
qemu_allocate_irqs(), which is almost always going to involve
it leaking memory. The fix is usually to rewrite the code to not use
that function at all, i.e. to manage its irq/gpio lines differently.
Probably the i8259 code should have a named GPIO output line
rather than wanting to be passed a qemu_irq in an init function,
and the via code should have an input GPIO line which it connects
up to the i8259. It looks from a quick glance like the i8259 and
its callers have perhaps not been completely QOMified.
Everything involving ISA emulation in QEMU is not completely QOMified and
this has caused some problems before but I did not want to try to fix it
both becuase it's too much unrelated work and because it's used by too
many things that could break that I can't even test. So I'd rather
somebody more comfortable with this would look at ISA QOMification.
In this specific case, though, it seems like the only thing that
the via_isa_request_i8259_irq() function does is pass the interrupt
signal through to its own s->cpu_intr, so I think a relatively
self-contained way to deal with the leak is to pass s->cpu_intr
into i8259_init() and drop the isa_irq allocated irq and its
associated helper function entirely. (There might be some subtlety
I'm missing that means that wouldn't work, of course.)
I think I've tried to do that first and it did not work for some reason
then I got this way from some other device model which works but I forgot
the details. You can test it by booting MorphOS or Debian Linux 8.11 PPC
on pegasos2 which support this machine or maybe I can have a look later
this week if it's not urgent and try something but I don't mind if
somebody comes up with a fix before that.
Regards,
BALATON Zoltan
