On Thu, Sep 02, 2021 at 08:36:56AM +0100, Peter Maydell wrote: > On Wed, 1 Sept 2021 at 21:24, Richard W.M. Jones <rjo...@redhat.com> wrote: > > > > On Wed, Sep 01, 2021 at 09:17:07PM +0100, Peter Maydell wrote: > > > On Wed, 1 Sept 2021 at 19:51, Richard W.M. Jones <rjo...@redhat.com> > > > wrote: > > > > > > > > On Wed, Sep 01, 2021 at 07:41:21PM +0100, Peter Maydell wrote: > > > > > Is the failure case short enough to allow -d ... logging to > > > > > be taken? That's usually the most useful info, but it's so huge > > > > > it's often not feasible. > > > > > > > > I can try -- what exact -d option would be useful? > > > > > > Depends what you're after. Personally I'm fairly sure I know > > > what's going on, I'm just not sure what the right fix is. > > > > Another question: We couldn't reproduce this even with the identical > > ARM guest kernel + initrd + command line using qemu-system-arm > > compiled for x86-64 host. This was a bit surprising! Was that bad > > luck or is there some reason why this bug might not be reproducible > > except on armv7 host? (Both cases use -machine accel=tcg). > > That's expected -- this is a bug in the codegen for arm hosts > (specifically 32-bit arm where Neon is available). tcg/i386/ > sets TCG_TARGET_STACK_ALIGN to 16, so it won't hit the assert. > > Yesterday I wrote: > > The prologue does seem to actively align to the > > specified value, not merely assume-and-preserve that alignment. > > but I was misreading the code -- it does just assume-and-preserve. > > Do you need an urgent fix/workaround for this? The simplest thing > is to wait for RTH to look at this, which is not likely to be before > the 13th.
We can wait for Richard to take a look. Thanks, Rich. > Otherwise I think you can work around it with: > > --- a/tcg/arm/tcg-target.h > +++ b/tcg/arm/tcg-target.h > @@ -152,7 +152,7 @@ extern bool use_neon_instructions; > #define TCG_TARGET_HAS_qemu_st8_i32 0 > > #define TCG_TARGET_HAS_v64 use_neon_instructions > -#define TCG_TARGET_HAS_v128 use_neon_instructions > +#define TCG_TARGET_HAS_v128 0 > #define TCG_TARGET_HAS_v256 0 > > #define TCG_TARGET_HAS_andc_vec 1 > > though this is just a bodge that (hopefully) turns the use of v128 > off entirely. > > -- PMM -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://libguestfs.org
