[Qemu-devel] [PATCH] build fix: xen on NetBSD/amd64

[Qemu-devel] [PATCH] build fix: xen on NetBSD/amd64

[Christoph Egger]

[-- Attachment #1: Type: text/plain, Size: 583 bytes --]


Hi!

Attached patch fixes this build error on NetBSD/amd64:

hw/xen_blkif.h:20: warning: #pragma pack(psuh[, id], <n>) is not supported on 
this target
hw/xen_blkif.h:36: warning: #pragma pack(pop[, id], <n>) is not supported on 
this target

Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>


-- 
---to satisfy European Law for business letters:
Advanced Micro Devices GmbH
Karl-Hammerschmidt-Str. 34, 85609 Dornach b. Muenchen
Geschaeftsfuehrer: Thomas M. McCoy, Giuliano Meroni
Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen
Registergericht Muenchen, HRB Nr. 43632

[-- Attachment #2: qemu_xen_blkif.diff --]
[-- Type: text/x-diff, Size: 1243 bytes --]

diff --git a/hw/xen_blkif.h b/hw/xen_blkif.h
index 738b8fe..bb4ff02 100644
--- a/hw/xen_blkif.h
+++ b/hw/xen_blkif.h
@@ -16,8 +16,9 @@ struct blkif_common_response {
 	char dummy;
 };
 
+/* XXX move this into a proper header */
+#define __aligned(x)	__attribute__((__aligned__(x)))
 /* i386 protocol version */
-#pragma pack(push, 4)
 struct blkif_x86_32_request {
 	uint8_t        operation;    /* BLKIF_OP_???                         */
 	uint8_t        nr_segments;  /* number of segments                   */
@@ -25,15 +26,14 @@ struct blkif_x86_32_request {
 	uint64_t       id;           /* private guest value, echoed in resp  */
 	blkif_sector_t sector_number;/* start sector idx on disk (r/w only)  */
 	struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
-};
+} __aligned(4);
 struct blkif_x86_32_response {
 	uint64_t        id;              /* copied from request */
 	uint8_t         operation;       /* copied from request */
 	int16_t         status;          /* BLKIF_RSP_???       */
-};
+} __aligned(4);
 typedef struct blkif_x86_32_request blkif_x86_32_request_t;
 typedef struct blkif_x86_32_response blkif_x86_32_response_t;
-#pragma pack(pop)
 
 /* x86_64 protocol version */
 struct blkif_x86_64_request {

Re: [Qemu-devel] [PATCH] build fix: xen on NetBSD/amd64

[Anthony Liguori]

Christoph Egger wrote:
> Hi!
>
> Attached patch fixes this build error on NetBSD/amd64:
>
> hw/xen_blkif.h:20: warning: #pragma pack(psuh[, id], <n>) is not supported on 
> this target
> hw/xen_blkif.h:36: warning: #pragma pack(pop[, id], <n>) is not supported on 
> this target
>
> Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>
>   

You'll invoke the fury of malc for introducing an identifier that begins 
with '__' :-)

There really isn't pragma pack on NetBSD?  That's ashame.

Regards,

Anthony Liguori

Re: [Qemu-devel] [PATCH] build fix: xen on NetBSD/amd64

[Christoph Egger]

On Thursday 09 July 2009 21:21:06 Anthony Liguori wrote:
> Christoph Egger wrote:
> > Hi!
> >
> > Attached patch fixes this build error on NetBSD/amd64:
> >
> > hw/xen_blkif.h:20: warning: #pragma pack(psuh[, id], <n>) is not
> > supported on this target
> > hw/xen_blkif.h:36: warning: #pragma pack(pop[, id], <n>) is not supported
> > on this target
> >
> > Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>
>
> You'll invoke the fury of malc for introducing an identifier that begins
> with '__' :-)

In NetBSD, there is this in <sys/cdefs.h> :

#if __GNUC_PREREQ__(2, 7)
#define __packed        __attribute__((__packed__))
#define __aligned(x)    __attribute__((__aligned__(x)))
#define __section(x)    __attribute__((__section__(x)))
#elif defined(__PCC__)
#define __packed        _Pragma("packed 1")
#define __aligned(x)    _Pragma("aligned " __STRING(x))
#define __section(x)    _Pragma("section " ## x)
#elif defined(__lint__)
#define __packed        /* delete */
#define __aligned(x)    /* delete */
#define __section(x)    /* delete */
#else
#define __packed        error: no __packed for this compiler
#define __aligned(x)    error: no __aligned for this compiler
#define __section(x)    error: no __section for this compiler
#endif


> There really isn't pragma pack on NetBSD?  That's ashame.

No. Above defines are sufficient and portable.
Now you know where the __aligned define in my patch comes from. :-)

Christoph


-- 
---to satisfy European Law for business letters:
Advanced Micro Devices GmbH
Karl-Hammerschmidt-Str. 34, 85609 Dornach b. Muenchen
Geschaeftsfuehrer: Thomas M. McCoy, Giuliano Meroni
Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen
Registergericht Muenchen, HRB Nr. 43632

Re: [Qemu-devel] [PATCH] build fix: xen on NetBSD/amd64

[malc]

On Fri, 10 Jul 2009, Christoph Egger wrote:

> On Thursday 09 July 2009 21:21:06 Anthony Liguori wrote:
> > Christoph Egger wrote:
> > > Hi!
> > >
> > > Attached patch fixes this build error on NetBSD/amd64:
> > >
> > > hw/xen_blkif.h:20: warning: #pragma pack(psuh[, id], <n>) is not
> > > supported on this target
> > > hw/xen_blkif.h:36: warning: #pragma pack(pop[, id], <n>) is not supported
> > > on this target
> > >
> > > Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>
> >
> > You'll invoke the fury of malc for introducing an identifier that begins
> > with '__' :-)
> 
> In NetBSD, there is this in <sys/cdefs.h> :
> 
> #if __GNUC_PREREQ__(2, 7)
> #define __packed        __attribute__((__packed__))
> #define __aligned(x)    __attribute__((__aligned__(x)))
> #define __section(x)    __attribute__((__section__(x)))
> #elif defined(__PCC__)
> #define __packed        _Pragma("packed 1")
> #define __aligned(x)    _Pragma("aligned " __STRING(x))
> #define __section(x)    _Pragma("section " ## x)
> #elif defined(__lint__)
> #define __packed        /* delete */
> #define __aligned(x)    /* delete */
> #define __section(x)    /* delete */
> #else
> #define __packed        error: no __packed for this compiler
> #define __aligned(x)    error: no __aligned for this compiler
> #define __section(x)    error: no __section for this compiler
> #endif
> 
> 
> > There really isn't pragma pack on NetBSD?  That's ashame.
> 
> No. Above defines are sufficient and portable.

Above defines are sufficient but not anywhere near portable.

> Now you know where the __aligned define in my patch comes from. :-)

You should conditionally include include sys/cdefs.h on NetBSD and not
defining your own version of __aligned (which is forbidden by the
standard).

Few more points:

 a. the file in question already uses aligned attribute _inside_ the
    structures without any macros

 b. unlike all other xen* files the header guard is __XEN_BLKIF_H__
    and not QEMU_XEN_BLKIF_H (that should be fixed too)

-- 
mailto:av1474@comtv.ru

Re: [Qemu-devel] [PATCH] build fix: xen on NetBSD/amd64

[Christoph Egger]

On Friday 10 July 2009 12:18:39 malc wrote:
> On Fri, 10 Jul 2009, Christoph Egger wrote:
> > On Thursday 09 July 2009 21:21:06 Anthony Liguori wrote:
> > > Christoph Egger wrote:
> > > > Hi!
> > > >
> > > > Attached patch fixes this build error on NetBSD/amd64:
> > > >
> > > > hw/xen_blkif.h:20: warning: #pragma pack(psuh[, id], <n>) is not
> > > > supported on this target
> > > > hw/xen_blkif.h:36: warning: #pragma pack(pop[, id], <n>) is not
> > > > supported on this target
> > > >
> > > > Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>
> > >
> > > You'll invoke the fury of malc for introducing an identifier that
> > > begins with '__' :-)
> >
> > In NetBSD, there is this in <sys/cdefs.h> :
> >
> > #if __GNUC_PREREQ__(2, 7)
> > #define __packed        __attribute__((__packed__))
> > #define __aligned(x)    __attribute__((__aligned__(x)))
> > #define __section(x)    __attribute__((__section__(x)))
> > #elif defined(__PCC__)
> > #define __packed        _Pragma("packed 1")
> > #define __aligned(x)    _Pragma("aligned " __STRING(x))
> > #define __section(x)    _Pragma("section " ## x)
> > #elif defined(__lint__)
> > #define __packed        /* delete */
> > #define __aligned(x)    /* delete */
> > #define __section(x)    /* delete */
> > #else
> > #define __packed        error: no __packed for this compiler
> > #define __aligned(x)    error: no __aligned for this compiler
> > #define __section(x)    error: no __section for this compiler
> > #endif
> >
> > > There really isn't pragma pack on NetBSD?  That's ashame.
> >
> > No. Above defines are sufficient and portable.
>
> Above defines are sufficient but not anywhere near portable.

Well, across different compilers, they are.


> > Now you know where the __aligned define in my patch comes from. :-)
>
> You should conditionally include include sys/cdefs.h on NetBSD and not
> defining your own version of __aligned (which is forbidden by the
> standard).

sys/cdefs.h is included implicitely by any libc standard header on NetBSD.
No need for an #ifdef __NetBSD__ ... #endif for this.

> Few more points:
>
>  a. the file in question already uses aligned attribute _inside_ the
>     structures without any macros

So the pragmas have no effect then ? If so, then just remove them.

>  b. unlike all other xen* files the header guard is __XEN_BLKIF_H__
>     and not QEMU_XEN_BLKIF_H (that should be fixed too)

Easy to fix. Will you do or should I send a diff ?

Christoph

-- 
---to satisfy European Law for business letters:
Advanced Micro Devices GmbH
Karl-Hammerschmidt-Str. 34, 85609 Dornach b. Muenchen
Geschaeftsfuehrer: Thomas M. McCoy, Giuliano Meroni
Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen
Registergericht Muenchen, HRB Nr. 43632

Re: [Qemu-devel] [PATCH] build fix: xen on NetBSD/amd64

[malc]

On Fri, 10 Jul 2009, Christoph Egger wrote:

> On Friday 10 July 2009 12:18:39 malc wrote:
> > On Fri, 10 Jul 2009, Christoph Egger wrote:
> > > On Thursday 09 July 2009 21:21:06 Anthony Liguori wrote:
> > > > Christoph Egger wrote:
> > > > > Hi!
> > > > >
> > > > > Attached patch fixes this build error on NetBSD/amd64:
> > > > >
> > > > > hw/xen_blkif.h:20: warning: #pragma pack(psuh[, id], <n>) is not
> > > > > supported on this target
> > > > > hw/xen_blkif.h:36: warning: #pragma pack(pop[, id], <n>) is not
> > > > > supported on this target
> > > > >
> > > > > Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>
> > > >
> > > > You'll invoke the fury of malc for introducing an identifier that
> > > > begins with '__' :-)
> > >
> > > In NetBSD, there is this in <sys/cdefs.h> :
> > >
> > > #if __GNUC_PREREQ__(2, 7)
> > > #define __packed        __attribute__((__packed__))
> > > #define __aligned(x)    __attribute__((__aligned__(x)))
> > > #define __section(x)    __attribute__((__section__(x)))
> > > #elif defined(__PCC__)
> > > #define __packed        _Pragma("packed 1")
> > > #define __aligned(x)    _Pragma("aligned " __STRING(x))
> > > #define __section(x)    _Pragma("section " ## x)
> > > #elif defined(__lint__)
> > > #define __packed        /* delete */
> > > #define __aligned(x)    /* delete */
> > > #define __section(x)    /* delete */
> > > #else
> > > #define __packed        error: no __packed for this compiler
> > > #define __aligned(x)    error: no __aligned for this compiler
> > > #define __section(x)    error: no __section for this compiler
> > > #endif
> > >
> > > > There really isn't pragma pack on NetBSD?  That's ashame.
> > >
> > > No. Above defines are sufficient and portable.
> >
> > Above defines are sufficient but not anywhere near portable.
> 
> Well, across different compilers, they are.

What i meant is that they (the system provider) are free to do that,
you (the user) can not do that though.
> 
> > > Now you know where the __aligned define in my patch comes from. :-)
> >
> > You should conditionally include include sys/cdefs.h on NetBSD and not
> > defining your own version of __aligned (which is forbidden by the
> > standard).
> 
> sys/cdefs.h is included implicitely by any libc standard header on NetBSD.
> No need for an #ifdef __NetBSD__ ... #endif for this.

Then i actually fail to see how your original patch is supposed to work
at all, gcc should raise hell about redefinition of __aligned.

> > Few more points:
> >
> >  a. the file in question already uses aligned attribute _inside_ the
> >     structures without any macros
> 
> So the pragmas have no effect then ? If so, then just remove them.

Not really, the individual members are marked with attribute aligned
(just take a look), not the whole structures.

> 
> >  b. unlike all other xen* files the header guard is __XEN_BLKIF_H__
> >     and not QEMU_XEN_BLKIF_H (that should be fixed too)
> 
> Easy to fix. Will you do or should I send a diff ?
> 

That would be very nice of you.

-- 
mailto:av1474@comtv.ru

Re: [Qemu-devel] [PATCH] build fix: xen on NetBSD/amd64

[Christoph Egger]

[-- Attachment #1: Type: text/plain, Size: 3576 bytes --]

On Friday 10 July 2009 17:22:04 malc wrote:
> On Fri, 10 Jul 2009, Christoph Egger wrote:
> > On Friday 10 July 2009 12:18:39 malc wrote:
> > > On Fri, 10 Jul 2009, Christoph Egger wrote:
> > > > On Thursday 09 July 2009 21:21:06 Anthony Liguori wrote:
> > > > > Christoph Egger wrote:
> > > > > > Hi!
> > > > > >
> > > > > > Attached patch fixes this build error on NetBSD/amd64:
> > > > > >
> > > > > > hw/xen_blkif.h:20: warning: #pragma pack(psuh[, id], <n>) is not
> > > > > > supported on this target
> > > > > > hw/xen_blkif.h:36: warning: #pragma pack(pop[, id], <n>) is not
> > > > > > supported on this target
> > > > > >
> > > > > > Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>
> > > > >
> > > > > You'll invoke the fury of malc for introducing an identifier that
> > > > > begins with '__' :-)
> > > >
> > > > In NetBSD, there is this in <sys/cdefs.h> :
> > > >
> > > > #if __GNUC_PREREQ__(2, 7)
> > > > #define __packed        __attribute__((__packed__))
> > > > #define __aligned(x)    __attribute__((__aligned__(x)))
> > > > #define __section(x)    __attribute__((__section__(x)))
> > > > #elif defined(__PCC__)
> > > > #define __packed        _Pragma("packed 1")
> > > > #define __aligned(x)    _Pragma("aligned " __STRING(x))
> > > > #define __section(x)    _Pragma("section " ## x)
> > > > #elif defined(__lint__)
> > > > #define __packed        /* delete */
> > > > #define __aligned(x)    /* delete */
> > > > #define __section(x)    /* delete */
> > > > #else
> > > > #define __packed        error: no __packed for this compiler
> > > > #define __aligned(x)    error: no __aligned for this compiler
> > > > #define __section(x)    error: no __section for this compiler
> > > > #endif
> > > >
> > > > > There really isn't pragma pack on NetBSD?  That's ashame.
> > > >
> > > > No. Above defines are sufficient and portable.
> > >
> > > Above defines are sufficient but not anywhere near portable.
> >
> > Well, across different compilers, they are.
>
> What i meant is that they (the system provider) are free to do that,
> you (the user) can not do that though.
>
> > > > Now you know where the __aligned define in my patch comes from. :-)
> > >
> > > You should conditionally include include sys/cdefs.h on NetBSD and not
> > > defining your own version of __aligned (which is forbidden by the
> > > standard).
> >
> > sys/cdefs.h is included implicitely by any libc standard header on
> > NetBSD. No need for an #ifdef __NetBSD__ ... #endif for this.
>
> Then i actually fail to see how your original patch is supposed to work
> at all, gcc should raise hell about redefinition of __aligned.
>
> > > Few more points:
> > >
> > >  a. the file in question already uses aligned attribute _inside_ the
> > >     structures without any macros
> >
> > So the pragmas have no effect then ? If so, then just remove them.
>
> Not really, the individual members are marked with attribute aligned
> (just take a look), not the whole structures.
>
> > >  b. unlike all other xen* files the header guard is __XEN_BLKIF_H__
> > >     and not QEMU_XEN_BLKIF_H (that should be fixed too)
> >
> > Easy to fix. Will you do or should I send a diff ?
>
> That would be very nice of you.

Is attached patch fine with you ?

Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>

-- 
---to satisfy European Law for business letters:
Advanced Micro Devices GmbH
Karl-Hammerschmidt-Str. 34, 85609 Dornach b. Muenchen
Geschaeftsfuehrer: Thomas M. McCoy, Giuliano Meroni
Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen
Registergericht Muenchen, HRB Nr. 43632

[-- Attachment #2: qemu_xen_blkif.diff --]
[-- Type: text/x-diff, Size: 1032 bytes --]

diff --git a/hw/xen_blkif.h b/hw/xen_blkif.h
index 738b8fe..f47f9a4 100644
--- a/hw/xen_blkif.h
+++ b/hw/xen_blkif.h
@@ -1,5 +1,5 @@
-#ifndef __XEN_BLKIF_H__
-#define __XEN_BLKIF_H__
+#ifndef __QEMU_BLKIF_H__
+#define __QEMU_BLKIF_H__
 
 #include <xen/io/ring.h>
 #include <xen/io/blkif.h>
@@ -17,7 +17,6 @@ struct blkif_common_response {
 };
 
 /* i386 protocol version */
-#pragma pack(push, 4)
 struct blkif_x86_32_request {
 	uint8_t        operation;    /* BLKIF_OP_???                         */
 	uint8_t        nr_segments;  /* number of segments                   */
@@ -33,7 +32,6 @@ struct blkif_x86_32_response {
 };
 typedef struct blkif_x86_32_request blkif_x86_32_request_t;
 typedef struct blkif_x86_32_response blkif_x86_32_response_t;
-#pragma pack(pop)
 
 /* x86_64 protocol version */
 struct blkif_x86_64_request {
@@ -100,4 +98,4 @@ static void inline blkif_get_x86_64_req(blkif_request_t *dst, blkif_x86_64_reque
 		dst->seg[i] = src->seg[i];
 }
 
-#endif /* __XEN_BLKIF_H__ */
+#endif /* __QEMU_BLKIF_H__ */

Re: [Qemu-devel] [PATCH] build fix: xen on NetBSD/amd64

[malc]

On Fri, 17 Jul 2009, Christoph Egger wrote:

> On Friday 10 July 2009 17:22:04 malc wrote:
> > On Fri, 10 Jul 2009, Christoph Egger wrote:
> > > On Friday 10 July 2009 12:18:39 malc wrote:
> > > > On Fri, 10 Jul 2009, Christoph Egger wrote:
> > > > > On Thursday 09 July 2009 21:21:06 Anthony Liguori wrote:
> > > > > > Christoph Egger wrote:
> > > > > > > Hi!
> > > > > > >
> > > > > > > Attached patch fixes this build error on NetBSD/amd64:
> > > > > > >
> > > > > > > hw/xen_blkif.h:20: warning: #pragma pack(psuh[, id], <n>) is not
> > > > > > > supported on this target
> > > > > > > hw/xen_blkif.h:36: warning: #pragma pack(pop[, id], <n>) is not
> > > > > > > supported on this target
> > > > > > >
> > > > > > > Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>
> > > > > >
> > > > > > You'll invoke the fury of malc for introducing an identifier that
> > > > > > begins with '__' :-)
> > > > >

[..snip..]

> >
> > That would be very nice of you.
> 
> Is attached patch fine with you ?
> 
> Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>
> 

No. It replaces one identifier starting with __ with another.

-- 
mailto:av1474@comtv.ru

Re: [Qemu-devel] [PATCH] build fix: xen on NetBSD/amd64

[Anthony Liguori]

Christoph Egger wrote:
> On Thursday 09 July 2009 21:21:06 Anthony Liguori wrote:
>   
>> Christoph Egger wrote:
>>     
>>> Hi!
>>>
>>> Attached patch fixes this build error on NetBSD/amd64:
>>>
>>> hw/xen_blkif.h:20: warning: #pragma pack(psuh[, id], <n>) is not
>>> supported on this target
>>> hw/xen_blkif.h:36: warning: #pragma pack(pop[, id], <n>) is not supported
>>> on this target
>>>
>>> Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>
>>>       
>> You'll invoke the fury of malc for introducing an identifier that begins
>> with '__' :-)
>>     
>
> In NetBSD, there is this in <sys/cdefs.h> :
>   

NetBSD is allowed to use these names in system headers but according to 
the C standard, normal programs like QEMU aren't.  So we need to use 
something other than __aligned.

Regards,

Anthony Liguori

Re: [Qemu-devel] [PATCH] build fix: xen on NetBSD/amd64

[Christoph Egger]

On Friday 10 July 2009 14:58:48 Anthony Liguori wrote:
> Christoph Egger wrote:
> > On Thursday 09 July 2009 21:21:06 Anthony Liguori wrote:
> >> Christoph Egger wrote:
> >>> Hi!
> >>>
> >>> Attached patch fixes this build error on NetBSD/amd64:
> >>>
> >>> hw/xen_blkif.h:20: warning: #pragma pack(psuh[, id], <n>) is not
> >>> supported on this target
> >>> hw/xen_blkif.h:36: warning: #pragma pack(pop[, id], <n>) is not
> >>> supported on this target
> >>>
> >>> Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>
> >>
> >> You'll invoke the fury of malc for introducing an identifier that begins
> >> with '__' :-)
> >
> > In NetBSD, there is this in <sys/cdefs.h> :
>
> NetBSD is allowed to use these names in system headers but according to
> the C standard, normal programs like QEMU aren't.  So we need to use
> something other than __aligned.

What about  __qemu_aligned ?

#ifdef __NetBSD__
#define __qemu_aligned(x)    __aligned(x)
#else
#define __qemu_aligned(x)    __attribute__((__aligned__(x)))
#endif


> Regards,
>
> Anthony Liguori



-- 
---to satisfy European Law for business letters:
Advanced Micro Devices GmbH
Karl-Hammerschmidt-Str. 34, 85609 Dornach b. Muenchen
Geschaeftsfuehrer: Thomas M. McCoy, Giuliano Meroni
Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen
Registergericht Muenchen, HRB Nr. 43632

Re: [Qemu-devel] [PATCH] build fix: xen on NetBSD/amd64

[malc]

On Fri, 10 Jul 2009, Christoph Egger wrote:

> On Friday 10 July 2009 14:58:48 Anthony Liguori wrote:
> > Christoph Egger wrote:
> > > On Thursday 09 July 2009 21:21:06 Anthony Liguori wrote:
> > >> Christoph Egger wrote:
> > >>> Hi!
> > >>>
> > >>> Attached patch fixes this build error on NetBSD/amd64:
> > >>>
> > >>> hw/xen_blkif.h:20: warning: #pragma pack(psuh[, id], <n>) is not
> > >>> supported on this target
> > >>> hw/xen_blkif.h:36: warning: #pragma pack(pop[, id], <n>) is not
> > >>> supported on this target
> > >>>
> > >>> Signed-off-by: Christoph Egger <Christoph.Egger@amd.com>
> > >>
> > >> You'll invoke the fury of malc for introducing an identifier that begins
> > >> with '__' :-)
> > >
> > > In NetBSD, there is this in <sys/cdefs.h> :
> >
> > NetBSD is allowed to use these names in system headers but according to
> > the C standard, normal programs like QEMU aren't.  So we need to use
> > something other than __aligned.
>
> What about  __qemu_aligned ?
>
> #ifdef __NetBSD__
> #define __qemu_aligned(x)    __aligned(x)
> #else
> #define __qemu_aligned(x)    __attribute__((__aligned__(x)))
> #endif

Let me quote the standard once again:

       7.1.3  Reserved identifiers
[..snip..]
         -- All  identifiers  that  begin  with  an  underscore and
            either an uppercase letter or  another  underscore  are
            always reserved for any use.

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