| Message ID | 59E4C2F80200007800186B29@prv-mh.provo.novell.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 16/10/17 13:32, Jan Beulich wrote: > Since the emulator acts on the live hardware registers, we need to > prevent the compiler from using them e.g. for inlined memcpy() / > memset() (as gcc7 does). We can't, however, set this from the command > line, as otherwise the 64-bit build would face issues with functions > returning floating point values and being declared in standard headers. > > As the pragma isn't available prior to gcc6, we need to invoke it > conditionally. Luckily up to gcc6 we haven't seen generated code access > SIMD registers beyond what our asm()s do. > > Reported-by: George Dunlap <george.dunlap@citrix.com> > Signed-off-by: Jan Beulich <jbeulich@suse.com> > --- > While this doesn't affect core functionality, I think it would still be > nice for it to be allowed in for 4.10. Agreed. Has this been tested with Clang? It stands a good chance of being compatible, but we may need an && !defined(__clang__) included. ~Andrew > > --- a/tools/tests/x86_emulator/x86-emulate.h > +++ b/tools/tests/x86_emulator/x86-emulate.h > @@ -4,6 +4,11 @@ > #include <stdint.h> > #include <stdlib.h> > #include <string.h> > + > +#if __GNUC__ >= 6 > +#pragma GCC target("no-sse") > +#endif > + > #include <xen/xen.h> > > #include <asm/msr-index.h> > > >
>>> On 16.10.17 at 14:37, <andrew.cooper3@citrix.com> wrote: > On 16/10/17 13:32, Jan Beulich wrote: >> Since the emulator acts on the live hardware registers, we need to >> prevent the compiler from using them e.g. for inlined memcpy() / >> memset() (as gcc7 does). We can't, however, set this from the command >> line, as otherwise the 64-bit build would face issues with functions >> returning floating point values and being declared in standard headers. >> >> As the pragma isn't available prior to gcc6, we need to invoke it >> conditionally. Luckily up to gcc6 we haven't seen generated code access >> SIMD registers beyond what our asm()s do. >> >> Reported-by: George Dunlap <george.dunlap@citrix.com> >> Signed-off-by: Jan Beulich <jbeulich@suse.com> >> --- >> While this doesn't affect core functionality, I think it would still be >> nice for it to be allowed in for 4.10. > > Agreed. > > Has this been tested with Clang? Sorry, no - still haven't got around to set up a suitable Clang locally. > It stands a good chance of being > compatible, but we may need an && !defined(__clang__) included. Should non-gcc silently ignore "#pragma GCC ..." it doesn't recognize, or not define __GNUC__ in the first place if it isn't sufficiently compatible? I.e. if anything I'd expect we need "#elif defined(__clang__)" to achieve the same for Clang by some different pragma (if such exists). Jan
On 10/16/2017 01:32 PM, Jan Beulich wrote: > Since the emulator acts on the live hardware registers, we need to > prevent the compiler from using them e.g. for inlined memcpy() / > memset() (as gcc7 does). Why doesn't this affect the rest of the hypervisor too, since we don't save and restore the *mm registers? > We can't, however, set this from the command > line, as otherwise the 64-bit build would face issues with functions > returning floating point values and being declared in standard headers. Sorry, just to clarify: You mean that there are standard headers which contain prototypes for functions which return floating point values; we include those headers but do not call the functions; and adding the #pragma to the command-line would cause the compiler to choke on the prototypes (even though the functions are never actually called)? -George
>>> On 16.10.17 at 17:05, <george.dunlap@citrix.com> wrote: > On 10/16/2017 01:32 PM, Jan Beulich wrote: >> Since the emulator acts on the live hardware registers, we need to >> prevent the compiler from using them e.g. for inlined memcpy() / >> memset() (as gcc7 does). > > Why doesn't this affect the rest of the hypervisor too, since we don't > save and restore the *mm registers? Because we build the hypervisor with -mno-sse. >> We can't, however, set this from the command >> line, as otherwise the 64-bit build would face issues with functions >> returning floating point values and being declared in standard headers. > > Sorry, just to clarify: You mean that there are standard headers which > contain prototypes for functions which return floating point values; we > include those headers but do not call the functions; and adding the > #pragma to the command-line would cause the compiler to choke on the > prototypes (even though the functions are never actually called)? Yes (adding the command line option equivalent of the pragma, that is). Jan
>>> On 16.10.17 at 14:42, wrote: >>>> On 16.10.17 at 14:37, <andrew.cooper3@citrix.com> wrote: > > On 16/10/17 13:32, Jan Beulich wrote: > >> Since the emulator acts on the live hardware registers, we need to > >> prevent the compiler from using them e.g. for inlined memcpy() / > >> memset() (as gcc7 does). We can't, however, set this from the command > >> line, as otherwise the 64-bit build would face issues with functions > >> returning floating point values and being declared in standard headers. > >> > >> As the pragma isn't available prior to gcc6, we need to invoke it > >> conditionally. Luckily up to gcc6 we haven't seen generated code access > >> SIMD registers beyond what our asm()s do. > >> > >> Reported-by: George Dunlap <george.dunlap@citrix.com> > >> Signed-off-by: Jan Beulich <jbeulich@suse.com> > >> --- > >> While this doesn't affect core functionality, I think it would still be > >> nice for it to be allowed in for 4.10. > > > > Agreed. > > > > Has this been tested with Clang? > > Sorry, no - still haven't got around to set up a suitable Clang > locally. > > > It stands a good chance of being > > compatible, but we may need an && !defined(__clang__) included. > > Should non-gcc silently ignore "#pragma GCC ..." it doesn't > recognize, or not define __GNUC__ in the first place if it isn't > sufficiently compatible? I.e. if anything I'd expect we need > "#elif defined(__clang__)" to achieve the same for Clang by > some different pragma (if such exists). Not having received any reply so far, I'm wondering whether being able to build the test harness with clang is more important than for it to work correctly when built with gcc. I can't predict when I would get around to set up a suitable clang on my dev systems. Jan
On 11/06/2017 11:59 AM, Jan Beulich wrote: >>>> On 16.10.17 at 14:42, wrote: >>>>> On 16.10.17 at 14:37, <andrew.cooper3@citrix.com> wrote: >>> On 16/10/17 13:32, Jan Beulich wrote: >>>> Since the emulator acts on the live hardware registers, we need to >>>> prevent the compiler from using them e.g. for inlined memcpy() / >>>> memset() (as gcc7 does). We can't, however, set this from the command >>>> line, as otherwise the 64-bit build would face issues with functions >>>> returning floating point values and being declared in standard headers. >>>> >>>> As the pragma isn't available prior to gcc6, we need to invoke it >>>> conditionally. Luckily up to gcc6 we haven't seen generated code access >>>> SIMD registers beyond what our asm()s do. >>>> >>>> Reported-by: George Dunlap <george.dunlap@citrix.com> >>>> Signed-off-by: Jan Beulich <jbeulich@suse.com> >>>> --- >>>> While this doesn't affect core functionality, I think it would still be >>>> nice for it to be allowed in for 4.10. >>> >>> Agreed. >>> >>> Has this been tested with Clang? >> >> Sorry, no - still haven't got around to set up a suitable Clang >> locally. >> >>> It stands a good chance of being >>> compatible, but we may need an && !defined(__clang__) included. >> >> Should non-gcc silently ignore "#pragma GCC ..." it doesn't >> recognize, or not define __GNUC__ in the first place if it isn't >> sufficiently compatible? I.e. if anything I'd expect we need >> "#elif defined(__clang__)" to achieve the same for Clang by >> some different pragma (if such exists). > > Not having received any reply so far, I'm wondering whether > being able to build the test harness with clang is more > important than for it to work correctly when built with gcc. I > can't predict when I would get around to set up a suitable > clang on my dev systems. I agree with the argument you make above. On the unlikely chance there's a problem Travis should catch it, and someone who actually has a clang setup can help sort it out. -George
Hi, On 11/06/2017 03:04 PM, George Dunlap wrote: > On 11/06/2017 11:59 AM, Jan Beulich wrote: >>>>> On 16.10.17 at 14:42, wrote: >>>>>> On 16.10.17 at 14:37, <andrew.cooper3@citrix.com> wrote: >>>> On 16/10/17 13:32, Jan Beulich wrote: >>>>> Since the emulator acts on the live hardware registers, we need to >>>>> prevent the compiler from using them e.g. for inlined memcpy() / >>>>> memset() (as gcc7 does). We can't, however, set this from the command >>>>> line, as otherwise the 64-bit build would face issues with functions >>>>> returning floating point values and being declared in standard headers. >>>>> >>>>> As the pragma isn't available prior to gcc6, we need to invoke it >>>>> conditionally. Luckily up to gcc6 we haven't seen generated code access >>>>> SIMD registers beyond what our asm()s do. >>>>> >>>>> Reported-by: George Dunlap <george.dunlap@citrix.com> >>>>> Signed-off-by: Jan Beulich <jbeulich@suse.com> >>>>> --- >>>>> While this doesn't affect core functionality, I think it would still be >>>>> nice for it to be allowed in for 4.10. >>>> >>>> Agreed. >>>> >>>> Has this been tested with Clang? >>> >>> Sorry, no - still haven't got around to set up a suitable Clang >>> locally. >>> >>>> It stands a good chance of being >>>> compatible, but we may need an && !defined(__clang__) included. >>> >>> Should non-gcc silently ignore "#pragma GCC ..." it doesn't >>> recognize, or not define __GNUC__ in the first place if it isn't >>> sufficiently compatible? I.e. if anything I'd expect we need >>> "#elif defined(__clang__)" to achieve the same for Clang by >>> some different pragma (if such exists). >> >> Not having received any reply so far, I'm wondering whether >> being able to build the test harness with clang is more >> important than for it to work correctly when built with gcc. I >> can't predict when I would get around to set up a suitable >> clang on my dev systems. > > I agree with the argument you make above. On the unlikely chance > there's a problem Travis should catch it, and someone who actually has a > clang setup can help sort it out. I am not entirely sure whether this count for a ack or not? I was waiting an Acked-by/Reviewed-by before consider the Release-Acked-by.
>>> On 06.11.17 at 16:04, <george.dunlap@citrix.com> wrote: > On 11/06/2017 11:59 AM, Jan Beulich wrote: >>>>> On 16.10.17 at 14:42, wrote: >>>>>> On 16.10.17 at 14:37, <andrew.cooper3@citrix.com> wrote: >>>> On 16/10/17 13:32, Jan Beulich wrote: >>>>> Since the emulator acts on the live hardware registers, we need to >>>>> prevent the compiler from using them e.g. for inlined memcpy() / >>>>> memset() (as gcc7 does). We can't, however, set this from the command >>>>> line, as otherwise the 64-bit build would face issues with functions >>>>> returning floating point values and being declared in standard headers. >>>>> >>>>> As the pragma isn't available prior to gcc6, we need to invoke it >>>>> conditionally. Luckily up to gcc6 we haven't seen generated code access >>>>> SIMD registers beyond what our asm()s do. >>>>> >>>>> Reported-by: George Dunlap <george.dunlap@citrix.com> >>>>> Signed-off-by: Jan Beulich <jbeulich@suse.com> >>>>> --- >>>>> While this doesn't affect core functionality, I think it would still be >>>>> nice for it to be allowed in for 4.10. >>>> >>>> Agreed. >>>> >>>> Has this been tested with Clang? >>> >>> Sorry, no - still haven't got around to set up a suitable Clang >>> locally. >>> >>>> It stands a good chance of being >>>> compatible, but we may need an && !defined(__clang__) included. >>> >>> Should non-gcc silently ignore "#pragma GCC ..." it doesn't >>> recognize, or not define __GNUC__ in the first place if it isn't >>> sufficiently compatible? I.e. if anything I'd expect we need >>> "#elif defined(__clang__)" to achieve the same for Clang by >>> some different pragma (if such exists). >> >> Not having received any reply so far, I'm wondering whether >> being able to build the test harness with clang is more >> important than for it to work correctly when built with gcc. I >> can't predict when I would get around to set up a suitable >> clang on my dev systems. > > I agree with the argument you make above. On the unlikely chance > there's a problem Travis should catch it, and someone who actually has a > clang setup can help sort it out. I'm still lacking an ack, before it being sensible to check with Julien whether this is still fine to go in at this late stage. Jan
On 21/11/17 13:26, Jan Beulich wrote: >>>> On 06.11.17 at 16:04, <george.dunlap@citrix.com> wrote: >> On 11/06/2017 11:59 AM, Jan Beulich wrote: >>>>>> On 16.10.17 at 14:42, wrote: >>>>>>> On 16.10.17 at 14:37, <andrew.cooper3@citrix.com> wrote: >>>>> On 16/10/17 13:32, Jan Beulich wrote: >>>>>> Since the emulator acts on the live hardware registers, we need to >>>>>> prevent the compiler from using them e.g. for inlined memcpy() / >>>>>> memset() (as gcc7 does). We can't, however, set this from the command >>>>>> line, as otherwise the 64-bit build would face issues with functions >>>>>> returning floating point values and being declared in standard headers. >>>>>> >>>>>> As the pragma isn't available prior to gcc6, we need to invoke it >>>>>> conditionally. Luckily up to gcc6 we haven't seen generated code access >>>>>> SIMD registers beyond what our asm()s do. >>>>>> >>>>>> Reported-by: George Dunlap <george.dunlap@citrix.com> >>>>>> Signed-off-by: Jan Beulich <jbeulich@suse.com> >>>>>> --- >>>>>> While this doesn't affect core functionality, I think it would still be >>>>>> nice for it to be allowed in for 4.10. >>>>> Agreed. >>>>> >>>>> Has this been tested with Clang? >>>> Sorry, no - still haven't got around to set up a suitable Clang >>>> locally. >>>> >>>>> It stands a good chance of being >>>>> compatible, but we may need an && !defined(__clang__) included. >>>> Should non-gcc silently ignore "#pragma GCC ..." it doesn't >>>> recognize, or not define __GNUC__ in the first place if it isn't >>>> sufficiently compatible? I.e. if anything I'd expect we need >>>> "#elif defined(__clang__)" to achieve the same for Clang by >>>> some different pragma (if such exists). >>> Not having received any reply so far, I'm wondering whether >>> being able to build the test harness with clang is more >>> important than for it to work correctly when built with gcc. I >>> can't predict when I would get around to set up a suitable >>> clang on my dev systems. >> I agree with the argument you make above. On the unlikely chance >> there's a problem Travis should catch it, and someone who actually has a >> clang setup can help sort it out. > I'm still lacking an ack, before it being sensible to check with Julien > whether this is still fine to go in at this late stage. Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Hi, On 11/21/2017 01:29 PM, Andrew Cooper wrote: > On 21/11/17 13:26, Jan Beulich wrote: >>>>> On 06.11.17 at 16:04, <george.dunlap@citrix.com> wrote: >>> On 11/06/2017 11:59 AM, Jan Beulich wrote: >>>>>>> On 16.10.17 at 14:42, wrote: >>>>>>>> On 16.10.17 at 14:37, <andrew.cooper3@citrix.com> wrote: >>>>>> On 16/10/17 13:32, Jan Beulich wrote: >>>>>>> Since the emulator acts on the live hardware registers, we need to >>>>>>> prevent the compiler from using them e.g. for inlined memcpy() / >>>>>>> memset() (as gcc7 does). We can't, however, set this from the command >>>>>>> line, as otherwise the 64-bit build would face issues with functions >>>>>>> returning floating point values and being declared in standard headers. >>>>>>> >>>>>>> As the pragma isn't available prior to gcc6, we need to invoke it >>>>>>> conditionally. Luckily up to gcc6 we haven't seen generated code access >>>>>>> SIMD registers beyond what our asm()s do. >>>>>>> >>>>>>> Reported-by: George Dunlap <george.dunlap@citrix.com> >>>>>>> Signed-off-by: Jan Beulich <jbeulich@suse.com> >>>>>>> --- >>>>>>> While this doesn't affect core functionality, I think it would still be >>>>>>> nice for it to be allowed in for 4.10. >>>>>> Agreed. >>>>>> >>>>>> Has this been tested with Clang? >>>>> Sorry, no - still haven't got around to set up a suitable Clang >>>>> locally. >>>>> >>>>>> It stands a good chance of being >>>>>> compatible, but we may need an && !defined(__clang__) included. >>>>> Should non-gcc silently ignore "#pragma GCC ..." it doesn't >>>>> recognize, or not define __GNUC__ in the first place if it isn't >>>>> sufficiently compatible? I.e. if anything I'd expect we need >>>>> "#elif defined(__clang__)" to achieve the same for Clang by >>>>> some different pragma (if such exists). >>>> Not having received any reply so far, I'm wondering whether >>>> being able to build the test harness with clang is more >>>> important than for it to work correctly when built with gcc. I >>>> can't predict when I would get around to set up a suitable >>>> clang on my dev systems. >>> I agree with the argument you make above. On the unlikely chance >>> there's a problem Travis should catch it, and someone who actually has a >>> clang setup can help sort it out. >> I'm still lacking an ack, before it being sensible to check with Julien >> whether this is still fine to go in at this late stage. I would be happy with that. Release-acked-by: Julien Grall <julien.grall@linaro.org> Cheers,
--- a/tools/tests/x86_emulator/x86-emulate.h +++ b/tools/tests/x86_emulator/x86-emulate.h @@ -4,6 +4,11 @@ #include <stdint.h> #include <stdlib.h> #include <string.h> + +#if __GNUC__ >= 6 +#pragma GCC target("no-sse") +#endif + #include <xen/xen.h> #include <asm/msr-index.h>
Since the emulator acts on the live hardware registers, we need to prevent the compiler from using them e.g. for inlined memcpy() / memset() (as gcc7 does). We can't, however, set this from the command line, as otherwise the 64-bit build would face issues with functions returning floating point values and being declared in standard headers. As the pragma isn't available prior to gcc6, we need to invoke it conditionally. Luckily up to gcc6 we haven't seen generated code access SIMD registers beyond what our asm()s do. Reported-by: George Dunlap <george.dunlap@citrix.com> Signed-off-by: Jan Beulich <jbeulich@suse.com> --- While this doesn't affect core functionality, I think it would still be nice for it to be allowed in for 4.10.