Re: [Xen-devel] Xen GCC coverage ARM64 testing - Unexpected Trap: Data Abort

[Viktor Mitin <viktor.mitin.19@xxxxxxxxx>]

Hi Wei and Julien,

Thank you for the hints provided. It is appeared that it was Yocto Xen
receipt issue and not Xen coverage feature issue.
We see that xencov* tools are built anyway, even in the case when
CONFIG_COVERAGE is not enabled in hypervisor Kconfig.
Is there a reason for this?

To summarize, there is no need to enable coverage feature in two
places, only in Kconfig, as mentioned in documentation.
It has been rechecked with Xen 4.12, and works well as expected.

---
Xen 4.13 has not been checked yet with the patch. Currently, xen 4.13
staging fails to boot due to unknown reason... it worked some days
ago.
It hangs after the next log currently:
(XEN) Failed to bring up CPU 7 (error -5)
(XEN) Brought up 4 CPUs
(XEN) P2M: 44-bit IPA with 44-bit PA and 8-bit VMID
(XEN) P2M: 4 levels with order-0 root, VTCR 0x80043594
(XEN) I/O virtualisation disabled
(XEN) build-id: f4ea2c93ff09225beed05f629a3813b4e31c420d
(XEN) alternatives: Patching with alt table 0000000000343d58 -> 0000000000344418
---

Julien, are you going to integrate the patch?

Thanks

On Mon, May 13, 2019 at 1:43 PM Wei Liu <wei.liu2@xxxxxxxxxx> wrote:
>
> On Mon, May 13, 2019 at 01:29:12PM +0300, Viktor Mitin wrote:
> > > > aarch64-poky-linux-gcc   -DBUILD_ID -fno-strict-aliasing -std=gnu99
> > > > -Wall -Wstrict-prototypes -Wdeclaration-after-statement
> > > > -Wno-unused-but-set-variable -Wno-unused-local-typedefs   -O2
> > > > -fomit-frame-pointer
> > > > -D__XEN_INTERFACE_VERSION__=__XEN_LATEST_INTERFACE_VERSION__ -MMD -MF
> > > > .handlereg.o.d -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE   -Werror
> > > > -Wmissing-prototypes -I./include
> > > > -I/home/c/w/rcar_h3_ubuntu1604_yocto/build/tmp/work/aarch64-poky-linux/xen/4.12.0.0+gitAUTOINC+fd2a34c965-r0/git/tools/libs/toolcore/../../../tools/include
> > > >   -c -o handlereg.o handlereg.c
> > >
> > > ... this looks like a tool building error when I only touch the
> > > hypervisor part. Are you certain this is my patch and not another error
> > > in Xen 4.12 (or any patch you have on top)?
> >
> > Julien, you are right, it was local environment build issue (sorry for 
> > that).
> > Xen GCC coverage feature works well with Aarch64 with this patch.
> > Checked both commands, xencov read and xencov reset - both work well
> > (no crashes anymore).
> >
> > Please also note that use case mentioned in Xen documentation
> > (xencov_split) is also ok with generated coverage.dat input:
> > xen.git/xen$ ssh root@host xencov read > coverage.dat
> > xen.git/xen$ ../tools/xencov_split coverage.dat --output-dir=/
> > xen.git/xen$ geninfo . -o cov.info
> > xen.git/xen$ genhtml cov.info -o cov/
> > xen.git/xen$ $BROWSER cov/index.html
> >
> > --------
> > Minor observation about coverage build procedure. Documentation states:
> > "To build with coverage support, enable CONFIG_COVERAGE in Kconfig."
> > However, to build it properly, it needs to enable coverage feature in
> > two places - main xen make command line and hypervisor .config file.
> > Is it expected way to build xen with coverage feature? If yes,
> > probably we should improve (or at least document) it some day...
>
> What does your make command line look like?
>
> Wei.

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