Re: [PATCH 2/2] hw/cxl: Allow tracing component I/O accesses

[Jonathan Cameron via <qemu-devel@nongnu.org>]

On Fri, 24 Jan 2025 17:28:02 +0100
Philippe Mathieu-Daudé <philmd@linaro.org> wrote:

> On 24/1/25 17:20, Jonathan Cameron wrote:
> > On Thu, 23 Jan 2025 09:51:51 +0000
> > Jonathan Cameron via <qemu-devel@nongnu.org> wrote:
> >   
> >> On Wed, 22 Jan 2025 07:56:24 +0100
> >> Philippe Mathieu-Daudé <philmd@linaro.org> wrote:
> >>  
> >>> Map the component I/O region as UnimplementedDevice
> >>> to be able to trace guest I/O accesses with '-d unimp'.
> >>>
> >>> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>  
> >> I'm not that familiar with this infrastructure but seems
> >> fine to me.
> >>
> >> I'd definitely be curious if anything is touching this space so
> >> tracing may be helpful for that!  
> > Hi Philippe
> >   
> >>
> >> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>  
> > Retract that.
> > 
> > Can't instantiate a CXL device with this patch because:
> > 
> > Device unimplemented-device can not be dynamically instantiated.  
> 
> Hmm the qtests using CXL devices pass, how do you trigger that?

Seems oddly enough to be arm64 only (well not x86 - there is
no support for other arches than those two) which isn't upstream yet
hence no tests upstream - I'll get back to that sometime soonish
as the blocker of dt-bindings for PXBs may be less of an issue than it was.

source of that print seems to be hw/core/sysbus-fdt.c
add_fdt_node(). Seems it is looking for sysbus devices and gets
confused when it finds this one. I'm not sure if it is in
/peripheral or /peripheral-anon.

For now you could try my gitlab tree
gitlab.com/jic23/qemu.git   cxl-* whatever has latest date.

Or shout if you want me to try anything.

Jonathan


> 
> > 
> > Reverting this patch on my tree fixes that.
> >   
> >>> ---
> >>>   include/hw/cxl/cxl_component.h |  3 ++-
> >>>   hw/cxl/cxl-component-utils.c   | 14 +++++++++++---
> >>>   hw/cxl/Kconfig                 |  1 +
> >>>   3 files changed, 14 insertions(+), 4 deletions(-)  
>