* Re: [Xen-devel] [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
@ 2019-05-21 9:55 ` Julien Grall
0 siblings, 0 replies; 22+ messages in thread
From: Julien Grall @ 2019-05-21 9:55 UTC (permalink / raw)
To: Jan Beulich
Cc: Andrew Cooper, Stefano Stabellini, Wei Liu, Ian Jackson, xen-devel
Hi Jan,
On 5/21/19 10:43 AM, Jan Beulich wrote:
>>>> On 21.05.19 at 11:35, <julien.grall@arm.com> wrote:
>> On 5/21/19 10:26 AM, Jan Beulich wrote:
>>>>>> On 20.05.19 at 20:12, <julien.grall@arm.com> wrote:
>>>> As this is now Xen and tools only, I am wondering whether the check on
>>>> GNU_C is still necessary. I am happy to send a follow-up patch (or fold
>>>> in this one) if it can be removed.
>>>
>>> I think this should be dropped if it can be without breaking any
>>> part of the build.
>> This is because all the tools are part of xen.git, right?
>
> Right - no-one else is supposed to define __XEN_TOOLS__, or
> if anyone does, they're on their own.
Thanks for the information. I will do a full build check.
>
>>>> --- a/xen/include/public/arch-arm.h
>>>> +++ b/xen/include/public/arch-arm.h
>>>> @@ -197,6 +197,7 @@
>>>> } while ( 0 )
>>>> #define set_xen_guest_handle(hnd, val) set_xen_guest_handle_raw(hnd, val)
>>>>
>>>> +#if defined(__XEN__) || defined(__XEN_TOOLS__)
>>>> #if defined(__GNUC__) && !defined(__STRICT_ANSI__)
>>>> /* Anonymous union includes both 32- and 64-bit names (e.g., r0/x0). */
>>>> # define __DECL_REG(n64, n32) union { \
>>>> @@ -272,6 +273,8 @@ DEFINE_XEN_GUEST_HANDLE(vcpu_guest_core_regs_t);
>>>>
>>>> #undef __DECL_REG
>>>>
>>>> +#endif
>>>
>>> If I was the maintainer of this code, I'd ask for the struct declaration
>>> to be moved (into the existing #if) rather than adding a 2nd #if.
>>
>> s/2nd/3rd/ ;)
>>
>> The reason I haven't done that is git will generate a completely
>> unrelated diff. So it makes quite difficult to understand the purpose of
>> the patch.
>
> Well, as said - you're the maintainer. I wouldn't be bothered overly
> much by a strange diff that might result.
I will wait on Stefano's input.
Cheers,
--
Julien Grall
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply [flat|nested] 22+ messages in thread* Re: [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
@ 2019-05-21 21:06 ` Stefano Stabellini
0 siblings, 0 replies; 22+ messages in thread
From: Stefano Stabellini @ 2019-05-21 21:06 UTC (permalink / raw)
To: Julien Grall
Cc: Stefano Stabellini, Wei Liu, Andrew Cooper, Ian Jackson,
Jan Beulich, xen-devel
On Tue, 21 May 2019, Julien Grall wrote:
> Hi Jan,
>
> On 5/21/19 10:43 AM, Jan Beulich wrote:
> > > > > On 21.05.19 at 11:35, <julien.grall@arm.com> wrote:
> > > On 5/21/19 10:26 AM, Jan Beulich wrote:
> > > > > > > On 20.05.19 at 20:12, <julien.grall@arm.com> wrote:
> > > > > As this is now Xen and tools only, I am wondering whether the
> > > > > check on
> > > > > GNU_C is still necessary. I am happy to send a follow-up patch
> > > > > (or fold
> > > > > in this one) if it can be removed.
> > > >
> > > > I think this should be dropped if it can be without breaking any
> > > > part of the build.
> > > This is because all the tools are part of xen.git, right?
> >
> > Right - no-one else is supposed to define __XEN_TOOLS__, or
> > if anyone does, they're on their own.
>
> Thanks for the information. I will do a full build check.
>
> >
> > > > > --- a/xen/include/public/arch-arm.h
> > > > > +++ b/xen/include/public/arch-arm.h
> > > > > @@ -197,6 +197,7 @@
> > > > > } while ( 0 )
> > > > > #define set_xen_guest_handle(hnd, val)
> > > > > set_xen_guest_handle_raw(hnd, val)
> > > > > +#if defined(__XEN__) || defined(__XEN_TOOLS__)
> > > > > #if defined(__GNUC__) && !defined(__STRICT_ANSI__)
> > > > > /* Anonymous union includes both 32- and 64-bit names (e.g.,
> > > > > r0/x0). */
> > > > > # define __DECL_REG(n64, n32) union { \
> > > > > @@ -272,6 +273,8 @@ DEFINE_XEN_GUEST_HANDLE(vcpu_guest_core_regs_t);
> > > > > #undef __DECL_REG
> > > > > +#endif
> > > >
> > > > If I was the maintainer of this code, I'd ask for the struct declaration
> > > > to be moved (into the existing #if) rather than adding a 2nd #if.
> > >
> > > s/2nd/3rd/ ;)
> > >
> > > The reason I haven't done that is git will generate a completely
> > > unrelated diff. So it makes quite difficult to understand the purpose of
> > > the patch.
> >
> > Well, as said - you're the maintainer. I wouldn't be bothered overly
> > much by a strange diff that might result.
>
> I will wait on Stefano's input.
Yes, please follow Jan's advice, thanks.
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https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply [flat|nested] 22+ messages in thread* Re: [Xen-devel] [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
@ 2019-05-21 21:06 ` Stefano Stabellini
0 siblings, 0 replies; 22+ messages in thread
From: Stefano Stabellini @ 2019-05-21 21:06 UTC (permalink / raw)
To: Julien Grall
Cc: Stefano Stabellini, Wei Liu, Andrew Cooper, Ian Jackson,
Jan Beulich, xen-devel
On Tue, 21 May 2019, Julien Grall wrote:
> Hi Jan,
>
> On 5/21/19 10:43 AM, Jan Beulich wrote:
> > > > > On 21.05.19 at 11:35, <julien.grall@arm.com> wrote:
> > > On 5/21/19 10:26 AM, Jan Beulich wrote:
> > > > > > > On 20.05.19 at 20:12, <julien.grall@arm.com> wrote:
> > > > > As this is now Xen and tools only, I am wondering whether the
> > > > > check on
> > > > > GNU_C is still necessary. I am happy to send a follow-up patch
> > > > > (or fold
> > > > > in this one) if it can be removed.
> > > >
> > > > I think this should be dropped if it can be without breaking any
> > > > part of the build.
> > > This is because all the tools are part of xen.git, right?
> >
> > Right - no-one else is supposed to define __XEN_TOOLS__, or
> > if anyone does, they're on their own.
>
> Thanks for the information. I will do a full build check.
>
> >
> > > > > --- a/xen/include/public/arch-arm.h
> > > > > +++ b/xen/include/public/arch-arm.h
> > > > > @@ -197,6 +197,7 @@
> > > > > } while ( 0 )
> > > > > #define set_xen_guest_handle(hnd, val)
> > > > > set_xen_guest_handle_raw(hnd, val)
> > > > > +#if defined(__XEN__) || defined(__XEN_TOOLS__)
> > > > > #if defined(__GNUC__) && !defined(__STRICT_ANSI__)
> > > > > /* Anonymous union includes both 32- and 64-bit names (e.g.,
> > > > > r0/x0). */
> > > > > # define __DECL_REG(n64, n32) union { \
> > > > > @@ -272,6 +273,8 @@ DEFINE_XEN_GUEST_HANDLE(vcpu_guest_core_regs_t);
> > > > > #undef __DECL_REG
> > > > > +#endif
> > > >
> > > > If I was the maintainer of this code, I'd ask for the struct declaration
> > > > to be moved (into the existing #if) rather than adding a 2nd #if.
> > >
> > > s/2nd/3rd/ ;)
> > >
> > > The reason I haven't done that is git will generate a completely
> > > unrelated diff. So it makes quite difficult to understand the purpose of
> > > the patch.
> >
> > Well, as said - you're the maintainer. I wouldn't be bothered overly
> > much by a strange diff that might result.
>
> I will wait on Stefano's input.
Yes, please follow Jan's advice, thanks.
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
@ 2019-05-22 12:20 ` Julien Grall
0 siblings, 0 replies; 22+ messages in thread
From: Julien Grall @ 2019-05-22 12:20 UTC (permalink / raw)
To: Jan Beulich
Cc: Andrew Cooper, Stefano Stabellini, Wei Liu, Ian Jackson, xen-devel
On 21/05/2019 10:55, Julien Grall wrote:
> Hi Jan,
>
> On 5/21/19 10:43 AM, Jan Beulich wrote:
>>>>> On 21.05.19 at 11:35, <julien.grall@arm.com> wrote:
>>> On 5/21/19 10:26 AM, Jan Beulich wrote:
>>>>>>> On 20.05.19 at 20:12, <julien.grall@arm.com> wrote:
>>>>> As this is now Xen and tools only, I am wondering whether the check on
>>>>> GNU_C is still necessary. I am happy to send a follow-up patch (or fold
>>>>> in this one) if it can be removed.
>>>>
>>>> I think this should be dropped if it can be without breaking any
>>>> part of the build.
>>> This is because all the tools are part of xen.git, right?
>>
>> Right - no-one else is supposed to define __XEN_TOOLS__, or
>> if anyone does, they're on their own.
>
> Thanks for the information. I will do a full build check.
I thought about this again, long term there are an attempt to build xen with
other compiler not necessarily supporting GNU C extension.
While this would probably not be the only place that need to be reworked, we
would have to revert part of this change. So I will not drop the #ifdef here.
I will resend the patch next week to give some time for more feedback.
Cheers,
--
Julien Grall
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [Xen-devel] [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
@ 2019-05-22 12:20 ` Julien Grall
0 siblings, 0 replies; 22+ messages in thread
From: Julien Grall @ 2019-05-22 12:20 UTC (permalink / raw)
To: Jan Beulich
Cc: Andrew Cooper, Stefano Stabellini, Wei Liu, Ian Jackson, xen-devel
On 21/05/2019 10:55, Julien Grall wrote:
> Hi Jan,
>
> On 5/21/19 10:43 AM, Jan Beulich wrote:
>>>>> On 21.05.19 at 11:35, <julien.grall@arm.com> wrote:
>>> On 5/21/19 10:26 AM, Jan Beulich wrote:
>>>>>>> On 20.05.19 at 20:12, <julien.grall@arm.com> wrote:
>>>>> As this is now Xen and tools only, I am wondering whether the check on
>>>>> GNU_C is still necessary. I am happy to send a follow-up patch (or fold
>>>>> in this one) if it can be removed.
>>>>
>>>> I think this should be dropped if it can be without breaking any
>>>> part of the build.
>>> This is because all the tools are part of xen.git, right?
>>
>> Right - no-one else is supposed to define __XEN_TOOLS__, or
>> if anyone does, they're on their own.
>
> Thanks for the information. I will do a full build check.
I thought about this again, long term there are an attempt to build xen with
other compiler not necessarily supporting GNU C extension.
While this would probably not be the only place that need to be reworked, we
would have to revert part of this change. So I will not drop the #ifdef here.
I will resend the patch next week to give some time for more feedback.
Cheers,
--
Julien Grall
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
@ 2019-05-22 12:29 ` Jan Beulich
0 siblings, 0 replies; 22+ messages in thread
From: Jan Beulich @ 2019-05-22 12:29 UTC (permalink / raw)
To: Julien Grall
Cc: Andrew Cooper, Stefano Stabellini, Wei Liu, Ian Jackson, xen-devel
>>> On 22.05.19 at 14:20, <julien.grall@arm.com> wrote:
>
> On 21/05/2019 10:55, Julien Grall wrote:
>> Hi Jan,
>>
>> On 5/21/19 10:43 AM, Jan Beulich wrote:
>>>>>> On 21.05.19 at 11:35, <julien.grall@arm.com> wrote:
>>>> On 5/21/19 10:26 AM, Jan Beulich wrote:
>>>>>>>> On 20.05.19 at 20:12, <julien.grall@arm.com> wrote:
>>>>>> As this is now Xen and tools only, I am wondering whether the check on
>>>>>> GNU_C is still necessary. I am happy to send a follow-up patch (or fold
>>>>>> in this one) if it can be removed.
>>>>>
>>>>> I think this should be dropped if it can be without breaking any
>>>>> part of the build.
>>>> This is because all the tools are part of xen.git, right?
>>>
>>> Right - no-one else is supposed to define __XEN_TOOLS__, or
>>> if anyone does, they're on their own.
>>
>> Thanks for the information. I will do a full build check.
>
> I thought about this again, long term there are an attempt to build xen with
> other compiler not necessarily supporting GNU C extension.
> While this would probably not be the only place that need to be reworked, we
> would have to revert part of this change. So I will not drop the #ifdef here.
Well, I don't know how it is for Arm, but on x86 we actually use the
"extended" naming quite extensively, so building with a compiler
that doesn't support this extension is not really an option there.
Jan
_______________________________________________
Xen-devel mailing list
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^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [Xen-devel] [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
@ 2019-05-22 12:29 ` Jan Beulich
0 siblings, 0 replies; 22+ messages in thread
From: Jan Beulich @ 2019-05-22 12:29 UTC (permalink / raw)
To: Julien Grall
Cc: Andrew Cooper, Stefano Stabellini, Wei Liu, Ian Jackson, xen-devel
>>> On 22.05.19 at 14:20, <julien.grall@arm.com> wrote:
>
> On 21/05/2019 10:55, Julien Grall wrote:
>> Hi Jan,
>>
>> On 5/21/19 10:43 AM, Jan Beulich wrote:
>>>>>> On 21.05.19 at 11:35, <julien.grall@arm.com> wrote:
>>>> On 5/21/19 10:26 AM, Jan Beulich wrote:
>>>>>>>> On 20.05.19 at 20:12, <julien.grall@arm.com> wrote:
>>>>>> As this is now Xen and tools only, I am wondering whether the check on
>>>>>> GNU_C is still necessary. I am happy to send a follow-up patch (or fold
>>>>>> in this one) if it can be removed.
>>>>>
>>>>> I think this should be dropped if it can be without breaking any
>>>>> part of the build.
>>>> This is because all the tools are part of xen.git, right?
>>>
>>> Right - no-one else is supposed to define __XEN_TOOLS__, or
>>> if anyone does, they're on their own.
>>
>> Thanks for the information. I will do a full build check.
>
> I thought about this again, long term there are an attempt to build xen with
> other compiler not necessarily supporting GNU C extension.
> While this would probably not be the only place that need to be reworked, we
> would have to revert part of this change. So I will not drop the #ifdef here.
Well, I don't know how it is for Arm, but on x86 we actually use the
"extended" naming quite extensively, so building with a compiler
that doesn't support this extension is not really an option there.
Jan
_______________________________________________
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^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
@ 2019-05-22 13:00 ` Julien Grall
0 siblings, 0 replies; 22+ messages in thread
From: Julien Grall @ 2019-05-22 13:00 UTC (permalink / raw)
To: Jan Beulich
Cc: Artem Mygaiev, Stefano Stabellini, Wei Liu, Andrew Cooper,
Ian Jackson, xen-devel
(+Artem)
Hi Jan,
On 22/05/2019 13:29, Jan Beulich wrote:
>>>> On 22.05.19 at 14:20, <julien.grall@arm.com> wrote:
>
>>
>> On 21/05/2019 10:55, Julien Grall wrote:
>>> Hi Jan,
>>>
>>> On 5/21/19 10:43 AM, Jan Beulich wrote:
>>>>>>> On 21.05.19 at 11:35, <julien.grall@arm.com> wrote:
>>>>> On 5/21/19 10:26 AM, Jan Beulich wrote:
>>>>>>>>> On 20.05.19 at 20:12, <julien.grall@arm.com> wrote:
>>>>>>> As this is now Xen and tools only, I am wondering whether the check on
>>>>>>> GNU_C is still necessary. I am happy to send a follow-up patch (or fold
>>>>>>> in this one) if it can be removed.
>>>>>>
>>>>>> I think this should be dropped if it can be without breaking any
>>>>>> part of the build.
>>>>> This is because all the tools are part of xen.git, right?
>>>>
>>>> Right - no-one else is supposed to define __XEN_TOOLS__, or
>>>> if anyone does, they're on their own.
>>>
>>> Thanks for the information. I will do a full build check.
>>
>> I thought about this again, long term there are an attempt to build xen with
>> other compiler not necessarily supporting GNU C extension.
>> While this would probably not be the only place that need to be reworked, we
>> would have to revert part of this change. So I will not drop the #ifdef here.
>
> Well, I don't know how it is for Arm, but on x86 we actually use the
> "extended" naming quite extensively, so building with a compiler
> that doesn't support this extension is not really an option there.
For the Arm, I think only cpu_user_regs is using "extended" naming. It should be
possible to remove it without too much trouble here.
@Artem, is there any restriction to use anonymous union in functional safety?
Cheers,
--
Julien Grall
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [Xen-devel] [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
@ 2019-05-22 13:00 ` Julien Grall
0 siblings, 0 replies; 22+ messages in thread
From: Julien Grall @ 2019-05-22 13:00 UTC (permalink / raw)
To: Jan Beulich
Cc: Artem Mygaiev, Stefano Stabellini, Wei Liu, Andrew Cooper,
Ian Jackson, xen-devel
(+Artem)
Hi Jan,
On 22/05/2019 13:29, Jan Beulich wrote:
>>>> On 22.05.19 at 14:20, <julien.grall@arm.com> wrote:
>
>>
>> On 21/05/2019 10:55, Julien Grall wrote:
>>> Hi Jan,
>>>
>>> On 5/21/19 10:43 AM, Jan Beulich wrote:
>>>>>>> On 21.05.19 at 11:35, <julien.grall@arm.com> wrote:
>>>>> On 5/21/19 10:26 AM, Jan Beulich wrote:
>>>>>>>>> On 20.05.19 at 20:12, <julien.grall@arm.com> wrote:
>>>>>>> As this is now Xen and tools only, I am wondering whether the check on
>>>>>>> GNU_C is still necessary. I am happy to send a follow-up patch (or fold
>>>>>>> in this one) if it can be removed.
>>>>>>
>>>>>> I think this should be dropped if it can be without breaking any
>>>>>> part of the build.
>>>>> This is because all the tools are part of xen.git, right?
>>>>
>>>> Right - no-one else is supposed to define __XEN_TOOLS__, or
>>>> if anyone does, they're on their own.
>>>
>>> Thanks for the information. I will do a full build check.
>>
>> I thought about this again, long term there are an attempt to build xen with
>> other compiler not necessarily supporting GNU C extension.
>> While this would probably not be the only place that need to be reworked, we
>> would have to revert part of this change. So I will not drop the #ifdef here.
>
> Well, I don't know how it is for Arm, but on x86 we actually use the
> "extended" naming quite extensively, so building with a compiler
> that doesn't support this extension is not really an option there.
For the Arm, I think only cpu_user_regs is using "extended" naming. It should be
possible to remove it without too much trouble here.
@Artem, is there any restriction to use anonymous union in functional safety?
Cheers,
--
Julien Grall
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
@ 2019-05-22 18:05 ` Artem Mygaiev
0 siblings, 0 replies; 22+ messages in thread
From: Artem Mygaiev @ 2019-05-22 18:05 UTC (permalink / raw)
To: JBeulich, julien.grall
Cc: wei.liu2, sstabellini, Ian.Jackson, xen-devel, andrew.cooper3
Hello Julien, Jan
On Wed, 2019-05-22 at 14:00 +0100, Julien Grall wrote:
> (+Artem)
>
> Hi Jan,
>
> On 22/05/2019 13:29, Jan Beulich wrote:
> > > > > On 22.05.19 at 14:20, <
> > > > > julien.grall@arm.com
> > > > > > wrote:
> > > On 21/05/2019 10:55, Julien Grall wrote:
> > > > Hi Jan,
> > > >
> > > > On 5/21/19 10:43 AM, Jan Beulich wrote:
> > > > > > > > On 21.05.19 at 11:35, <
> > > > > > > > julien.grall@arm.com
> > > > > > > > > wrote:
> > > > > >
> > > > > > On 5/21/19 10:26 AM, Jan Beulich wrote:
> > > > > > > > > > On 20.05.19 at 20:12, <
> > > > > > > > > > julien.grall@arm.com
> > > > > > > > > > > wrote:
> > > > > > > >
> > > > > > > > As this is now Xen and tools only, I am
> > > > > > > > wondering whether the check on
> > > > > > > > GNU_C is still necessary. I am happy to send a
> > > > > > > > follow-up patch (or fold
> > > > > > > > in this one) if it can be removed.
> > > > > > >
> > > > > > > I think this should be dropped if it can be without
> > > > > > > breaking any
> > > > > > > part of the build.
> > > > > >
> > > > > > This is because all the tools are part of xen.git, right?
> > > > >
> > > > > Right - no-one else is supposed to define __XEN_TOOLS__, or
> > > > > if anyone does, they're on their own.
> > > >
> > > > Thanks for the information. I will do a full build check.
> > >
> > > I thought about this again, long term there are an attempt to
> > > build xen with
> > > other compiler not necessarily supporting GNU C extension.
> > > While this would probably not be the only place that need to be
> > > reworked, we
> > > would have to revert part of this change. So I will not drop the
> > > #ifdef here.
> >
> > Well, I don't know how it is for Arm, but on x86 we actually use
> > the
> > "extended" naming quite extensively, so building with a compiler
> > that doesn't support this extension is not really an option there.
>
> For the Arm, I think only cpu_user_regs is using "extended" naming.
> It should be
> possible to remove it without too much trouble here.
>
> @Artem, is there any restriction to use anonymous union in functional
> safety?
>
In general, unions are not allowed in safety regulated programming,
they always require a "deviation" - e.g. unions use for data packing is
usually accepted disregarding anonymous or not.
Couple of other things I wanted to mention:
1. all protective programming standards e.g. MISRA recommend reducing
visibility of functions and variables to reduce API surface ans thus
need for test coverage and systematic fault probability.
2. current implementation xen tools are very hard to use in safety for
many reasons, I hope to follow up on this soon...
-- Artem
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^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [Xen-devel] [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
@ 2019-05-22 18:05 ` Artem Mygaiev
0 siblings, 0 replies; 22+ messages in thread
From: Artem Mygaiev @ 2019-05-22 18:05 UTC (permalink / raw)
To: JBeulich, julien.grall
Cc: wei.liu2, sstabellini, Ian.Jackson, xen-devel, andrew.cooper3
Hello Julien, Jan
On Wed, 2019-05-22 at 14:00 +0100, Julien Grall wrote:
> (+Artem)
>
> Hi Jan,
>
> On 22/05/2019 13:29, Jan Beulich wrote:
> > > > > On 22.05.19 at 14:20, <
> > > > > julien.grall@arm.com
> > > > > > wrote:
> > > On 21/05/2019 10:55, Julien Grall wrote:
> > > > Hi Jan,
> > > >
> > > > On 5/21/19 10:43 AM, Jan Beulich wrote:
> > > > > > > > On 21.05.19 at 11:35, <
> > > > > > > > julien.grall@arm.com
> > > > > > > > > wrote:
> > > > > >
> > > > > > On 5/21/19 10:26 AM, Jan Beulich wrote:
> > > > > > > > > > On 20.05.19 at 20:12, <
> > > > > > > > > > julien.grall@arm.com
> > > > > > > > > > > wrote:
> > > > > > > >
> > > > > > > > As this is now Xen and tools only, I am
> > > > > > > > wondering whether the check on
> > > > > > > > GNU_C is still necessary. I am happy to send a
> > > > > > > > follow-up patch (or fold
> > > > > > > > in this one) if it can be removed.
> > > > > > >
> > > > > > > I think this should be dropped if it can be without
> > > > > > > breaking any
> > > > > > > part of the build.
> > > > > >
> > > > > > This is because all the tools are part of xen.git, right?
> > > > >
> > > > > Right - no-one else is supposed to define __XEN_TOOLS__, or
> > > > > if anyone does, they're on their own.
> > > >
> > > > Thanks for the information. I will do a full build check.
> > >
> > > I thought about this again, long term there are an attempt to
> > > build xen with
> > > other compiler not necessarily supporting GNU C extension.
> > > While this would probably not be the only place that need to be
> > > reworked, we
> > > would have to revert part of this change. So I will not drop the
> > > #ifdef here.
> >
> > Well, I don't know how it is for Arm, but on x86 we actually use
> > the
> > "extended" naming quite extensively, so building with a compiler
> > that doesn't support this extension is not really an option there.
>
> For the Arm, I think only cpu_user_regs is using "extended" naming.
> It should be
> possible to remove it without too much trouble here.
>
> @Artem, is there any restriction to use anonymous union in functional
> safety?
>
In general, unions are not allowed in safety regulated programming,
they always require a "deviation" - e.g. unions use for data packing is
usually accepted disregarding anonymous or not.
Couple of other things I wanted to mention:
1. all protective programming standards e.g. MISRA recommend reducing
visibility of functions and variables to reduce API surface ans thus
need for test coverage and systematic fault probability.
2. current implementation xen tools are very hard to use in safety for
many reasons, I hope to follow up on this soon...
-- Artem
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
@ 2019-06-02 10:37 ` Julien Grall
0 siblings, 0 replies; 22+ messages in thread
From: Julien Grall @ 2019-06-02 10:37 UTC (permalink / raw)
To: Artem Mygaiev, JBeulich
Cc: wei.liu2, sstabellini, Ian.Jackson, xen-devel, andrew.cooper3
Hi Artem,
On 5/22/19 7:05 PM, Artem Mygaiev wrote:
> On Wed, 2019-05-22 at 14:00 +0100, Julien Grall wrote:
>> On 22/05/2019 13:29, Jan Beulich wrote:
>>>>>> On 22.05.19 at 14:20, <
>>>>>> julien.grall@arm.com
>>>>>>> wrote:
>>>> On 21/05/2019 10:55, Julien Grall wrote:
>>>>> Hi Jan,
>>>>>
>>>>> On 5/21/19 10:43 AM, Jan Beulich wrote:
>>>>>>>>> On 21.05.19 at 11:35, <
>>>>>>>>> julien.grall@arm.com
>>>>>>>>>> wrote:
>>>>>>>
>>>>>>> On 5/21/19 10:26 AM, Jan Beulich wrote:
>>>>>>>>>>> On 20.05.19 at 20:12, <
>>>>>>>>>>> julien.grall@arm.com
>>>>>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>> As this is now Xen and tools only, I am
>>>>>>>>> wondering whether the check on
>>>>>>>>> GNU_C is still necessary. I am happy to send a
>>>>>>>>> follow-up patch (or fold
>>>>>>>>> in this one) if it can be removed.
>>>>>>>>
>>>>>>>> I think this should be dropped if it can be without
>>>>>>>> breaking any
>>>>>>>> part of the build
>>>>>>>
>>>>>>> This is because all the tools are part of xen.git, right?
>>>>>>
>>>>>> Right - no-one else is supposed to define __XEN_TOOLS__, or
>>>>>> if anyone does, they're on their own.
>>>>>
>>>>> Thanks for the information. I will do a full build check.
>>>>
>>>> I thought about this again, long term there are an attempt to
>>>> build xen with
>>>> other compiler not necessarily supporting GNU C extension.
>>>> While this would probably not be the only place that need to be
>>>> reworked, we
>>>> would have to revert part of this change. So I will not drop the
>>>> #ifdef here.
>>>
>>> Well, I don't know how it is for Arm, but on x86 we actually use
>>> the
>>> "extended" naming quite extensively, so building with a compiler
>>> that doesn't support this extension is not really an option there.
>>
>> For the Arm, I think only cpu_user_regs is using "extended" naming.
>> It should be
>> possible to remove it without too much trouble here.
>>
>> @Artem, is there any restriction to use anonymous union in functional
>> safety?
>>
>
> In general, unions are not allowed in safety regulated programming,
> they always require a "deviation" - e.g. unions use for data packing is
> usually accepted disregarding anonymous or not.
That's good to know. I am going to keep for now the two definitions of
__DECL_REG. We can remove them later on if it is not necessary.
>
> Couple of other things I wanted to mention:
> 1. all protective programming standards e.g. MISRA recommend reducing
> visibility of functions and variables to reduce API surface ans thus
> need for test coverage and systematic fault probability.
In general, we want to limit the API exposed to guest as this is stable.
Let us know if you see other places where we could potentially reduce
the API without impacting existing guest.
> 2. current implementation xen tools are very hard to use in safety for
> many reasons, I hope to follow up on this soon...
Thank you for the feedback!
Cheers,
--
Julien Grall
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: [Xen-devel] [PATCH] xen/public: arch-arm: Restrict the visibility of struct vcpu_guest_core_regs
@ 2019-06-02 10:37 ` Julien Grall
0 siblings, 0 replies; 22+ messages in thread
From: Julien Grall @ 2019-06-02 10:37 UTC (permalink / raw)
To: Artem Mygaiev, JBeulich
Cc: wei.liu2, sstabellini, Ian.Jackson, xen-devel, andrew.cooper3
Hi Artem,
On 5/22/19 7:05 PM, Artem Mygaiev wrote:
> On Wed, 2019-05-22 at 14:00 +0100, Julien Grall wrote:
>> On 22/05/2019 13:29, Jan Beulich wrote:
>>>>>> On 22.05.19 at 14:20, <
>>>>>> julien.grall@arm.com
>>>>>>> wrote:
>>>> On 21/05/2019 10:55, Julien Grall wrote:
>>>>> Hi Jan,
>>>>>
>>>>> On 5/21/19 10:43 AM, Jan Beulich wrote:
>>>>>>>>> On 21.05.19 at 11:35, <
>>>>>>>>> julien.grall@arm.com
>>>>>>>>>> wrote:
>>>>>>>
>>>>>>> On 5/21/19 10:26 AM, Jan Beulich wrote:
>>>>>>>>>>> On 20.05.19 at 20:12, <
>>>>>>>>>>> julien.grall@arm.com
>>>>>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>> As this is now Xen and tools only, I am
>>>>>>>>> wondering whether the check on
>>>>>>>>> GNU_C is still necessary. I am happy to send a
>>>>>>>>> follow-up patch (or fold
>>>>>>>>> in this one) if it can be removed.
>>>>>>>>
>>>>>>>> I think this should be dropped if it can be without
>>>>>>>> breaking any
>>>>>>>> part of the build
>>>>>>>
>>>>>>> This is because all the tools are part of xen.git, right?
>>>>>>
>>>>>> Right - no-one else is supposed to define __XEN_TOOLS__, or
>>>>>> if anyone does, they're on their own.
>>>>>
>>>>> Thanks for the information. I will do a full build check.
>>>>
>>>> I thought about this again, long term there are an attempt to
>>>> build xen with
>>>> other compiler not necessarily supporting GNU C extension.
>>>> While this would probably not be the only place that need to be
>>>> reworked, we
>>>> would have to revert part of this change. So I will not drop the
>>>> #ifdef here.
>>>
>>> Well, I don't know how it is for Arm, but on x86 we actually use
>>> the
>>> "extended" naming quite extensively, so building with a compiler
>>> that doesn't support this extension is not really an option there.
>>
>> For the Arm, I think only cpu_user_regs is using "extended" naming.
>> It should be
>> possible to remove it without too much trouble here.
>>
>> @Artem, is there any restriction to use anonymous union in functional
>> safety?
>>
>
> In general, unions are not allowed in safety regulated programming,
> they always require a "deviation" - e.g. unions use for data packing is
> usually accepted disregarding anonymous or not.
That's good to know. I am going to keep for now the two definitions of
__DECL_REG. We can remove them later on if it is not necessary.
>
> Couple of other things I wanted to mention:
> 1. all protective programming standards e.g. MISRA recommend reducing
> visibility of functions and variables to reduce API surface ans thus
> need for test coverage and systematic fault probability.
In general, we want to limit the API exposed to guest as this is stable.
Let us know if you see other places where we could potentially reduce
the API without impacting existing guest.
> 2. current implementation xen tools are very hard to use in safety for
> many reasons, I hope to follow up on this soon...
Thank you for the feedback!
Cheers,
--
Julien Grall
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
^ permalink raw reply [flat|nested] 22+ messages in thread