Summary: v2 of fixing an assert due to mismatch of the
PL011 state struct size between the Rust and C impls.
Changes v1->v2:
* in patch 3, adjust 'use' statements to maintain alpha order and to
prefer 'size_of' and 'qemu_api::bindings::PL011State' over
'mem::size_of' and 'bindings::PL011State'.
All patches are reviewed.
NOTE: I won't be around to do a v3 of this series next week,
I'm afraid, so if it needs any further tweaks I'd appreciate
if somebody else could pick it up and make those, since this is
a bug we need to fix for 10.0.
More detailed info, same as v1 cover letter, below:
We have some users of the PL011 struct which embed it directly into
their own state structs. This means that the Rust version of the
device must have a state struct that is the same size or smaller
than the C struct.
In commit 9b642097d6b7 ("rust: pl011: switch to safe chardev operation")
the Rust PL011 state struct changed from having a bindings::CharBackend
to a chardev::CharBackend, which made it grow larger than the C
version. This results in an assertion at startup when QEMU was
built with Rust enabled:
$ qemu-system-arm -M raspi2b -display none
ERROR:../../qom/object.c:562:object_initialize_with_type: assertion
failed: (size >= type->instance_size)
This series fixes that by the simple expedient of adding
a padding field to the end of the C struct to ensure that
it's big enough to also fit the Rust version of the device.
It also moves the failure from runtime to compiletime,
by adding a Rust compile-time assert that it hasn't made
the state bigger than the C one, so if we do this again
it should be caught before it gets into git. (We don't
need to do the same thing for the HPET device, because there
the HPETState is a private implementation detail of the C
code, not exposed to its users.)
thanks
-- PMM
Paolo Bonzini (1):
rust: assertions: add static_assert
Peter Maydell (2):
hw/char/pl011: Pad PL011State struct to same size as Rust impl
rust: pl011: Check size of state struct at compile time
include/hw/char/pl011.h | 5 +++++
rust/wrapper.h | 1 +
rust/hw/char/pl011/src/device.rs | 9 ++++++++-
rust/qemu-api/src/assertions.rs | 22 ++++++++++++++++++++++
4 files changed, 36 insertions(+), 1 deletion(-)
--
2.43.0
