On Tue, 2022-06-14 at 20:11 +0200, Jan Kiszka wrote:
> On 08.06.22 18:59, Bezdeka, Florian (T CED SES-DE) wrote:
> > On Wed, 2022-06-08 at 17:02 +0200, Jan Kiszka wrote:
> > > On 25.05.22 11:56, Florian Bezdeka wrote:
> > > > Parts of the FPU tests were skipped when one of the following config
> > > > options was enabled, shadowing a real test issue that was triggered by
> > > > high load on the system. The options:
> > > >   - CONFIG_X86_USE_3DNOW
> > > >   - CONFIG_MD_RAID456
> > > >   - CONFIG_MD_RAID456_MODULE
> > > > 
> > > > As the FPU initialization is fixed now, we can enable the tests
> > > > unconditionally.
> > > > 
> > > > Signed-off-by: Florian Bezdeka <[email protected]>
> > > > ---
> > > >  .../arch/x86/ipipe/include/asm/xenomai/fptest.h     | 13 -------------
> > > >  1 file changed, 13 deletions(-)
> > > > 
> > > > diff --git a/kernel/cobalt/arch/x86/ipipe/include/asm/xenomai/fptest.h 
> > > > b/kernel/cobalt/arch/x86/ipipe/include/asm/xenomai/fptest.h
> > > > index ccf7afa11..7a2b17d75 100644
> > > > --- a/kernel/cobalt/arch/x86/ipipe/include/asm/xenomai/fptest.h
> > > > +++ b/kernel/cobalt/arch/x86/ipipe/include/asm/xenomai/fptest.h
> > > > @@ -36,19 +36,6 @@ static inline void fp_init(void)
> > > > 
> > > >  static inline int fp_linux_begin(void)
> > > >  {
> > > > -#if defined(CONFIG_X86_USE_3DNOW) \
> > > > -   || defined(CONFIG_MD_RAID456) || defined(CONFIG_MD_RAID456_MODULE)
> > > > -   /* Ther kernel uses x86 FPU, we can not also use it in our tests. */
> > > > -   static int once = 0;
> > > > -   if (!once) {
> > > > -           once = 1;
> > > > -           printk("%s:%d: Warning: Linux is compiled to use FPU in "
> > > > -                  "kernel-space.\nFor this reason, switchtest can not "
> > > > -                  "test using FPU in Linux kernel-space.\n",
> > > > -                  __FILE__, __LINE__);
> > > > -   }
> > > > -   return -EBUSY;
> > > > -#endif /* 3DNow or RAID 456 */
> > > >     kernel_fpu_begin();
> > > >     /* kernel_fpu_begin() does no re-initialize the fpu context, but
> > > >        fp_regs_set() implicitely expects an initialized fpu context, so
> > > 
> > > Hmm, I'm not yet fully convinced from reading both commit logs that the
> > > one fix actually obsoletes this check. Did it really only paper over a
> > > simple bug?
> > 
> > I don't have the full history here, but it seems that this was kind of
> > double protection.
> > 
> > So far all tests did not bring up any further issues.
> > 
> > On systems with RAID (=systems with one of the mentioned options
> > enabled) FPU usage is much more likely and bugs would trigger more
> > likely. I would like to enable the FPU systems especially on such
> > systems.
> > 
> > But: In case we have more undiscovered bugs in this area, it might
> > happen that we damage a RAID based file system. It seems Gilles had
> > such a system and tried to prevent FS damage this way.
> > 
> 
> OK, it's just a test setup in the end - let's dare it.
> 
> Applied both to stable/v3.2.

I have prepared backports for stable/v3.1.x and stable/v3.0.x as well.
If there is interest I could easily send them out. I was just waiting
for feedback to avoid reworking them all.

Do we try to keep the stable branches "synchronized" even for testing
issues?

> 
> Jan
> 

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