[Qemu-devel] [PATCH] dma/i82374: avoid double creation of i82374 device

[Qemu-devel] [PATCH] dma/i82374: avoid double creation of i82374 device

[Eduardo Otubo]

QEMU fails when used with the following command line:

  ./ppc64-softmmu/qemu-system-ppc64 -S -machine 40p,accel=tcg -device i82374
  qemu-system-ppc64: hw/isa/isa-bus.c:110: isa_bus_dma: Assertion `!bus->dma[0] && !bus->dma[1]' failed.
  Aborted (core dumped)

The 40p machine type already creates the device i82374. If specified in the
command line, it will try to create it again, hence generating the error. The
function isa_bus_dma() isn't supposed to be called twice for the same bus. One
way to avoid this problem is to set user_creatable=false.

A possible fix in a near future would be making
isa_bus_dma()/DMA_init()/i82374_realize() return an error instead of asserting
as well.

Signed-off-by: Eduardo Otubo <otubo@redhat.com>
---
 hw/dma/i82374.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/hw/dma/i82374.c b/hw/dma/i82374.c
index 6c0f975df0..e76dea8dc7 100644
--- a/hw/dma/i82374.c
+++ b/hw/dma/i82374.c
@@ -139,6 +139,11 @@ static void i82374_class_init(ObjectClass *klass, void *data)
     dc->realize = i82374_realize;
     dc->vmsd = &vmstate_i82374;
     dc->props = i82374_properties;
+    dc->user_creatable = false;
+    /*
+     * Reason: i82374_realize() crashes (assertion failure inside isa_bus_dma()
+     *         if the device is instantiated twice.
+     */
 }
 
 static const TypeInfo i82374_info = {
-- 
2.13.5

Re: [Qemu-devel] [Qemu-trivial] [PATCH] dma/i82374: avoid double creation of i82374 device

[Eduardo Otubo]

(oups, forgot the v2 on Subject)

On Fri, Sep 15, 2017 at 11:06:43AM +0200, Eduardo Otubo wrote:
> QEMU fails when used with the following command line:
> 
>   ./ppc64-softmmu/qemu-system-ppc64 -S -machine 40p,accel=tcg -device i82374
>   qemu-system-ppc64: hw/isa/isa-bus.c:110: isa_bus_dma: Assertion `!bus->dma[0] && !bus->dma[1]' failed.
>   Aborted (core dumped)
> 
> The 40p machine type already creates the device i82374. If specified in the
> command line, it will try to create it again, hence generating the error. The
> function isa_bus_dma() isn't supposed to be called twice for the same bus. One
> way to avoid this problem is to set user_creatable=false.
> 
> A possible fix in a near future would be making
> isa_bus_dma()/DMA_init()/i82374_realize() return an error instead of asserting
> as well.
> 
> Signed-off-by: Eduardo Otubo <otubo@redhat.com>
> ---
>  hw/dma/i82374.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/hw/dma/i82374.c b/hw/dma/i82374.c
> index 6c0f975df0..e76dea8dc7 100644
> --- a/hw/dma/i82374.c
> +++ b/hw/dma/i82374.c
> @@ -139,6 +139,11 @@ static void i82374_class_init(ObjectClass *klass, void *data)
>      dc->realize = i82374_realize;
>      dc->vmsd = &vmstate_i82374;
>      dc->props = i82374_properties;
> +    dc->user_creatable = false;
> +    /*
> +     * Reason: i82374_realize() crashes (assertion failure inside isa_bus_dma()
> +     *         if the device is instantiated twice.
> +     */
>  }
>  
>  static const TypeInfo i82374_info = {
> -- 
> 2.13.5
> 
> 

-- 
Eduardo Otubo
Senior Software Engineer @ RedHat

Re: [Qemu-devel] [PATCH] dma/i82374: avoid double creation of i82374 device

[Paolo Bonzini]

On 15/09/2017 11:06, Eduardo Otubo wrote:
> QEMU fails when used with the following command line:
> 
>   ./ppc64-softmmu/qemu-system-ppc64 -S -machine 40p,accel=tcg -device i82374
>   qemu-system-ppc64: hw/isa/isa-bus.c:110: isa_bus_dma: Assertion `!bus->dma[0] && !bus->dma[1]' failed.
>   Aborted (core dumped)
> 
> The 40p machine type already creates the device i82374. If specified in the
> command line, it will try to create it again, hence generating the error. The
> function isa_bus_dma() isn't supposed to be called twice for the same bus. One
> way to avoid this problem is to set user_creatable=false.
> 
> A possible fix in a near future would be making
> isa_bus_dma()/DMA_init()/i82374_realize() return an error instead of asserting
> as well.
> 
> Signed-off-by: Eduardo Otubo <otubo@redhat.com>
> ---
>  hw/dma/i82374.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/hw/dma/i82374.c b/hw/dma/i82374.c
> index 6c0f975df0..e76dea8dc7 100644
> --- a/hw/dma/i82374.c
> +++ b/hw/dma/i82374.c
> @@ -139,6 +139,11 @@ static void i82374_class_init(ObjectClass *klass, void *data)
>      dc->realize = i82374_realize;
>      dc->vmsd = &vmstate_i82374;
>      dc->props = i82374_properties;
> +    dc->user_creatable = false;
> +    /*
> +     * Reason: i82374_realize() crashes (assertion failure inside isa_bus_dma()
> +     *         if the device is instantiated twice.
> +     */
>  }
>  
>  static const TypeInfo i82374_info = {
> 

This breaks "make check", doesn't it?

v2 should be the one that returns an error instead of asserting.

Paolo

Re: [Qemu-devel] [PATCH] dma/i82374: avoid double creation of i82374 device

[Eduardo Otubo]

On Fri, Sep 15, 2017 at 12:18:11PM +0200, Paolo Bonzini wrote:
> On 15/09/2017 11:06, Eduardo Otubo wrote:
> > QEMU fails when used with the following command line:
> > 
> >   ./ppc64-softmmu/qemu-system-ppc64 -S -machine 40p,accel=tcg -device i82374
> >   qemu-system-ppc64: hw/isa/isa-bus.c:110: isa_bus_dma: Assertion `!bus->dma[0] && !bus->dma[1]' failed.
> >   Aborted (core dumped)
> > 
> > The 40p machine type already creates the device i82374. If specified in the
> > command line, it will try to create it again, hence generating the error. The
> > function isa_bus_dma() isn't supposed to be called twice for the same bus. One
> > way to avoid this problem is to set user_creatable=false.
> > 
> > A possible fix in a near future would be making
> > isa_bus_dma()/DMA_init()/i82374_realize() return an error instead of asserting
> > as well.
> > 
> > Signed-off-by: Eduardo Otubo <otubo@redhat.com>
> > ---
> >  hw/dma/i82374.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/hw/dma/i82374.c b/hw/dma/i82374.c
> > index 6c0f975df0..e76dea8dc7 100644
> > --- a/hw/dma/i82374.c
> > +++ b/hw/dma/i82374.c
> > @@ -139,6 +139,11 @@ static void i82374_class_init(ObjectClass *klass, void *data)
> >      dc->realize = i82374_realize;
> >      dc->vmsd = &vmstate_i82374;
> >      dc->props = i82374_properties;
> > +    dc->user_creatable = false;
> > +    /*
> > +     * Reason: i82374_realize() crashes (assertion failure inside isa_bus_dma()
> > +     *         if the device is instantiated twice.
> > +     */
> >  }
> >  
> >  static const TypeInfo i82374_info = {
> > 
> 
> This breaks "make check", doesn't it?
> 
> v2 should be the one that returns an error instead of asserting.

I guess I have misunderstood, then. I'll work on a patch to propagate
the error then.

Thanks,

-- 
Eduardo Otubo
Senior Software Engineer @ RedHat

Re: [Qemu-devel] [PATCH] dma/i82374: avoid double creation of i82374 device

[Eduardo Habkost]

On Fri, Sep 15, 2017 at 12:18:11PM +0200, Paolo Bonzini wrote:
> On 15/09/2017 11:06, Eduardo Otubo wrote:
> > QEMU fails when used with the following command line:
> > 
> >   ./ppc64-softmmu/qemu-system-ppc64 -S -machine 40p,accel=tcg -device i82374
> >   qemu-system-ppc64: hw/isa/isa-bus.c:110: isa_bus_dma: Assertion `!bus->dma[0] && !bus->dma[1]' failed.
> >   Aborted (core dumped)
> > 
> > The 40p machine type already creates the device i82374. If specified in the
> > command line, it will try to create it again, hence generating the error. The
> > function isa_bus_dma() isn't supposed to be called twice for the same bus. One
> > way to avoid this problem is to set user_creatable=false.
> > 
> > A possible fix in a near future would be making
> > isa_bus_dma()/DMA_init()/i82374_realize() return an error instead of asserting
> > as well.
> > 
> > Signed-off-by: Eduardo Otubo <otubo@redhat.com>
> > ---
> >  hw/dma/i82374.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/hw/dma/i82374.c b/hw/dma/i82374.c
> > index 6c0f975df0..e76dea8dc7 100644
> > --- a/hw/dma/i82374.c
> > +++ b/hw/dma/i82374.c
> > @@ -139,6 +139,11 @@ static void i82374_class_init(ObjectClass *klass, void *data)
> >      dc->realize = i82374_realize;
> >      dc->vmsd = &vmstate_i82374;
> >      dc->props = i82374_properties;
> > +    dc->user_creatable = false;
> > +    /*
> > +     * Reason: i82374_realize() crashes (assertion failure inside isa_bus_dma()
> > +     *         if the device is instantiated twice.
> > +     */
> >  }
> >  
> >  static const TypeInfo i82374_info = {
> > 
> 
> This breaks "make check", doesn't it?

Why would it?  I don't see any test code using -device i82374.
(endianness-test uses -device i82378).

> 
> v2 should be the one that returns an error instead of asserting.

I agree that returning an error is better.

-- 
Eduardo

Re: [Qemu-devel] [PATCH] dma/i82374: avoid double creation of i82374 device

[Paolo Bonzini]

----- Original Message -----
> From: "Eduardo Habkost" <ehabkost@redhat.com>
> To: "Paolo Bonzini" <pbonzini@redhat.com>
> Cc: "Eduardo Otubo" <otubo@redhat.com>, qemu-devel@nongnu.org, qemu-trivial@nongnu.org, "Michael Tokarev"
> <mjt@tls.msk.ru>, "Markus Armbruster" <armbru@redhat.com>, "Alexander Graf" <agraf@suse.de>
> Sent: Saturday, September 16, 2017 12:21:13 AM
> Subject: Re: [PATCH] dma/i82374: avoid double creation of i82374 device
> 
> On Fri, Sep 15, 2017 at 12:18:11PM +0200, Paolo Bonzini wrote:
> > On 15/09/2017 11:06, Eduardo Otubo wrote:
> > > QEMU fails when used with the following command line:
> > > 
> > >   ./ppc64-softmmu/qemu-system-ppc64 -S -machine 40p,accel=tcg -device
> > >   i82374
> > >   qemu-system-ppc64: hw/isa/isa-bus.c:110: isa_bus_dma: Assertion
> > >   `!bus->dma[0] && !bus->dma[1]' failed.
> > >   Aborted (core dumped)
> > > 
> > > The 40p machine type already creates the device i82374. If specified in
> > > the
> > > command line, it will try to create it again, hence generating the error.
> > > The
> > > function isa_bus_dma() isn't supposed to be called twice for the same
> > > bus. One
> > > way to avoid this problem is to set user_creatable=false.
> > > 
> > > A possible fix in a near future would be making
> > > isa_bus_dma()/DMA_init()/i82374_realize() return an error instead of
> > > asserting
> > > as well.
> > > 
> > > Signed-off-by: Eduardo Otubo <otubo@redhat.com>
> > > ---
> > >  hw/dma/i82374.c | 5 +++++
> > >  1 file changed, 5 insertions(+)
> > > 
> > > diff --git a/hw/dma/i82374.c b/hw/dma/i82374.c
> > > index 6c0f975df0..e76dea8dc7 100644
> > > --- a/hw/dma/i82374.c
> > > +++ b/hw/dma/i82374.c
> > > @@ -139,6 +139,11 @@ static void i82374_class_init(ObjectClass *klass,
> > > void *data)
> > >      dc->realize = i82374_realize;
> > >      dc->vmsd = &vmstate_i82374;
> > >      dc->props = i82374_properties;
> > > +    dc->user_creatable = false;
> > > +    /*
> > > +     * Reason: i82374_realize() crashes (assertion failure inside
> > > isa_bus_dma()
> > > +     *         if the device is instantiated twice.
> > > +     */
> > >  }
> > >  
> > >  static const TypeInfo i82374_info = {
> > > 
> > 
> > This breaks "make check", doesn't it?
> 
> Why would it?  I don't see any test code using -device i82374.
> (endianness-test uses -device i82378).

You're right, both Aurelien and I were confused.  If you want to
accept this patch it would be fine then, even if giving an error may
be preferrable.

Paolo

Re: [Qemu-devel] [[PATCH] dma/i82374: avoid double creation of i82374 device

[Michael Tokarev]

15.09.2017 12:06, Eduardo Otubo wrote:
> QEMU fails when used with the following command line:
> 
>   ./ppc64-softmmu/qemu-system-ppc64 -S -machine 40p,accel=tcg -device i82374
>   qemu-system-ppc64: hw/isa/isa-bus.c:110: isa_bus_dma: Assertion `!bus->dma[0] && !bus->dma[1]' failed.
>   Aborted (core dumped)
> 
> The 40p machine type already creates the device i82374. If specified in the
> command line, it will try to create it again, hence generating the error. The
> function isa_bus_dma() isn't supposed to be called twice for the same bus. One
> way to avoid this problem is to set user_creatable=false.

Applied to -trivial, thanks!

/mjt

Re: [Qemu-devel] [[PATCH] dma/i82374: avoid double creation of i82374 device

[Paolo Bonzini]

On 24/09/2017 23:02, Michael Tokarev wrote:
> 15.09.2017 12:06, Eduardo Otubo wrote:
>> QEMU fails when used with the following command line:
>>
>>   ./ppc64-softmmu/qemu-system-ppc64 -S -machine 40p,accel=tcg -device i82374
>>   qemu-system-ppc64: hw/isa/isa-bus.c:110: isa_bus_dma: Assertion `!bus->dma[0] && !bus->dma[1]' failed.
>>   Aborted (core dumped)
>>
>> The 40p machine type already creates the device i82374. If specified in the
>> command line, it will try to create it again, hence generating the error. The
>> function isa_bus_dma() isn't supposed to be called twice for the same bus. One
>> way to avoid this problem is to set user_creatable=false.
> 
> Applied to -trivial, thanks!

Eduardo, weren't you going to send a version that propagates Error*
correctly instead?

Paolo

Re: [Qemu-devel] [[PATCH] dma/i82374: avoid double creation of i82374 device

[Eduardo Otubo]

On Mon, Sep 25, 2017 at 11:11:37AM +0200, Paolo Bonzini wrote:
> On 24/09/2017 23:02, Michael Tokarev wrote:
> > 15.09.2017 12:06, Eduardo Otubo wrote:
> >> QEMU fails when used with the following command line:
> >>
> >>   ./ppc64-softmmu/qemu-system-ppc64 -S -machine 40p,accel=tcg -device i82374
> >>   qemu-system-ppc64: hw/isa/isa-bus.c:110: isa_bus_dma: Assertion `!bus->dma[0] && !bus->dma[1]' failed.
> >>   Aborted (core dumped)
> >>
> >> The 40p machine type already creates the device i82374. If specified in the
> >> command line, it will try to create it again, hence generating the error. The
> >> function isa_bus_dma() isn't supposed to be called twice for the same bus. One
> >> way to avoid this problem is to set user_creatable=false.
> > 
> > Applied to -trivial, thanks!
> 
> Eduardo, weren't you going to send a version that propagates Error*
> correctly instead?

Yes, that's correct. I can revert this patch with the error
propagation patch as well, if you guys don't mind.

Re: [Qemu-devel] [[PATCH] dma/i82374: avoid double creation of i82374 device

[Paolo Bonzini]

On 25/09/2017 11:26, Eduardo Otubo wrote:
> On Mon, Sep 25, 2017 at 11:11:37AM +0200, Paolo Bonzini wrote:
>> On 24/09/2017 23:02, Michael Tokarev wrote:
>>> 15.09.2017 12:06, Eduardo Otubo wrote:
>>>> QEMU fails when used with the following command line:
>>>>
>>>>   ./ppc64-softmmu/qemu-system-ppc64 -S -machine 40p,accel=tcg -device i82374
>>>>   qemu-system-ppc64: hw/isa/isa-bus.c:110: isa_bus_dma: Assertion `!bus->dma[0] && !bus->dma[1]' failed.
>>>>   Aborted (core dumped)
>>>>
>>>> The 40p machine type already creates the device i82374. If specified in the
>>>> command line, it will try to create it again, hence generating the error. The
>>>> function isa_bus_dma() isn't supposed to be called twice for the same bus. One
>>>> way to avoid this problem is to set user_creatable=false.
>>>
>>> Applied to -trivial, thanks!
>>
>> Eduardo, weren't you going to send a version that propagates Error*
>> correctly instead?
> 
> Yes, that's correct. I can revert this patch with the error
> propagation patch as well, if you guys don't mind.

Sure, that's fine too.

Paolo

Re: [Qemu-devel] [PATCH] dma/i82374: avoid double creation of i82374 device

[Michael Tokarev]

25.09.2017 12:26, Eduardo Otubo wrote:
> On Mon, Sep 25, 2017 at 11:11:37AM +0200, Paolo Bonzini wrote:
>> On 24/09/2017 23:02, Michael Tokarev wrote:
>>> 15.09.2017 12:06, Eduardo Otubo wrote:
>>>> QEMU fails when used with the following command line:
>>>>
>>>>   ./ppc64-softmmu/qemu-system-ppc64 -S -machine 40p,accel=tcg -device i82374
>>>>   qemu-system-ppc64: hw/isa/isa-bus.c:110: isa_bus_dma: Assertion `!bus->dma[0] && !bus->dma[1]' failed.
>>>>   Aborted (core dumped)
>>>>
>>>> The 40p machine type already creates the device i82374. If specified in the
>>>> command line, it will try to create it again, hence generating the error. The
>>>> function isa_bus_dma() isn't supposed to be called twice for the same bus. One
>>>> way to avoid this problem is to set user_creatable=false.
>>>
>>> Applied to -trivial, thanks!
>>
>> Eduardo, weren't you going to send a version that propagates Error*
>> correctly instead?
> 
> Yes, that's correct. I can revert this patch with the error
> propagation patch as well, if you guys don't mind.

Hmm. After reading the original discussion I concluded this patch
is okay.  I can remove it right now before the series has been
applied, together with another tiny change.

Thanks,

/mjt

Re: [Qemu-devel] [PATCH] dma/i82374: avoid double creation of i82374 device

[Paolo Bonzini]

On 25/09/2017 12:54, Michael Tokarev wrote:
>> Yes, that's correct. I can revert this patch with the error
>> propagation patch as well, if you guys don't mind.
> Hmm. After reading the original discussion I concluded this patch
> is okay.  I can remove it right now before the series has been
> applied, together with another tiny change.

No problem, it's okay for now as a trivial change.

Paolo

Re: [Qemu-devel] [Qemu-trivial] [PATCH] dma/i82374: avoid double creation of i82374 device

[Eduardo Habkost]

On Thu, Sep 07, 2017 at 10:38:29AM +0200, Eduardo Otubo wrote:
> On Fri, Sep 01, 2017 at 12:44:30PM -0300, Eduardo Habkost wrote:
> > On Fri, Sep 01, 2017 at 05:34:34PM +0200, Markus Armbruster wrote:
> > > Eduardo Habkost <ehabkost@redhat.com> writes:
> > > > On Fri, Sep 01, 2017 at 01:03:32PM +0200, Eduardo Otubo wrote:
[...]
> > > >> diff --git a/hw/dma/i82374.c b/hw/dma/i82374.c
> > > >> index 6c0f975df0..5275d822e0 100644
> > > >> --- a/hw/dma/i82374.c
> > > >> +++ b/hw/dma/i82374.c
> > > >> @@ -139,6 +139,7 @@ static void i82374_class_init(ObjectClass *klass, void *data)
> > > >>      dc->realize = i82374_realize;
> > > >>      dc->vmsd = &vmstate_i82374;
> > > >>      dc->props = i82374_properties;
> > > >> +    dc->user_creatable = false;
> > > >
> > > > A "Reason:" comment explaining why user_creatable=false is
> > > > mandatory.  See the comment above user_creatable declaration in
> > > > qdev-core.h for reference.
> > > >
> > > > I suggest the following:
> > > >
> > > >     /*
> > > >      * Reason: i82374_realize() crashes (assertion failure inside isa_bus_dma()
> > > >      *         if the device is instantiated twice.
> > > >      */
> 
> I agree with the comment above. If there's nothing left to fix/add
> I'll just send a v2 for this shortly.

I suggest amending it with the additional info below, explaining
that isa_bus_dma() isn't supposed to be called twice, and that we
need to make isa_bus_dma()/DMA_init()/i82374_realize() return an
appropriate error if the device is instantiated twice.


> 
> > > 
> > > We need to find out *why* it crashes.  Once we know, we can likely write
> > > a better comment.
> > 
> > It crashes because isa_bus_dma() isn't supposed to be called
> > twice for the same bus.
> > 
> > Making isa_bus_dma()/DMA_init()/i82374_realize() return an error
> > instead of asserting would be even better than setting
> > user_creatable=false.
> > 
> > -- 
> > Eduardo
> > 
> 
> -- 
> Eduardo Otubo
> Senior Software Engineer @ RedHat

-- 
Eduardo

Re: [Qemu-devel] [Qemu-trivial] [PATCH] dma/i82374: avoid double creation of i82374 device

[Eduardo Otubo]

On Thu, Sep 07, 2017 at 06:05:37PM +0200, Paolo Bonzini wrote:
> Il 02 set 2017 11:17 AM, "Aurelien Jarno" <aurelien@aurel32.net> ha scritto:
> 
> On 2017-09-01 11:30, Eduardo Habkost wrote:
> > i82374 is compiled in only on ppc and sh4, so I'm CCing the
> > maintainers for those architectures.
> 
> The i82374 device is not useful nor usable on SH4. It has just been
> added in commit 85d3846a39 to be able to run the tests.
> 
> 
> But that means that the patch is wrong and probably was not tested with
> "make check".
> 
> Eduardo's proposal is the right one.
> 

Great, I'll just add the missing details and resend the v2. Thanks for
the review.

Regards,

-- 
Eduardo Otubo
Senior Software Engineer @ RedHat

Re: [Qemu-devel] [Qemu-trivial] [PATCH] dma/i82374: avoid double creation of i82374 device

[Eduardo Otubo]

On Sat, Sep 02, 2017 at 11:15:20AM +0200, Aurelien Jarno wrote:
> On 2017-09-01 11:30, Eduardo Habkost wrote:
> > i82374 is compiled in only on ppc and sh4, so I'm CCing the
> > maintainers for those architectures.
> 
> The i82374 device is not useful nor usable on SH4. It has just been
> added in commit 85d3846a39 to be able to run the tests.
> 
> Aurelien
> 

Any word from the ppc guys?

-- 
Eduardo Otubo
Senior Software Engineer @ RedHat

Re: [Qemu-devel] [Qemu-trivial] [PATCH] dma/i82374: avoid double creation of i82374 device

[Eduardo Otubo]

On Fri, Sep 01, 2017 at 12:44:30PM -0300, Eduardo Habkost wrote:
> On Fri, Sep 01, 2017 at 05:34:34PM +0200, Markus Armbruster wrote:
> > Eduardo Habkost <ehabkost@redhat.com> writes:
> > 
> > > i82374 is compiled in only on ppc and sh4, so I'm CCing the
> > > maintainers for those architectures.
> > >
> > > On Fri, Sep 01, 2017 at 01:03:32PM +0200, Eduardo Otubo wrote:
> > >> When used with the following command line:
> > >> 
> > >>  ./ppc64-softmmu/qemu-system-ppc64 -S -machine 40p,accel=tcg -device i82374
> > >> 
> > >> QEMU with machine type 40p already creates the device i82374. If
> > >> specified in the command line, it will try to create it again, hence
> > >> generating the error.

Well pointed, forgot to describe the actual error. I may inlcude for
the next version of the patch. For for correctness sake, here it is:

 ./ppc64-softmmu/qemu-system-ppc64 -S -machine 40p,accel=tcg -device i82374
 qemu-system-ppc64: hw/isa/isa-bus.c:110: isa_bus_dma: Assertion `!bus->dma[0] && !bus->dma[1]' failed.
 Aborted (core dumped)

> > >
> > > Which error?
> > >
> > >
> > >>                       One way to avoid this problem is to set
> > >> user_creatable=false.
> > >> 
> > >> Signed-off-by: Eduardo Otubo <otubo@redhat.com>
> > >
> > > The patch does more than just avoiding double creation: it
> > > prevents usage of "-device i82374" completely.
> > >
> > > Maybe nobody needs it to work with -device today (would the
> > > device even work?) and it is OK to set user_creatable=false until
> > > we fix the crash.  But we need to be sure of that.
> > >
> > >> ---
> > >>  hw/dma/i82374.c | 1 +
> > >>  1 file changed, 1 insertion(+)
> > >> 
> > >> diff --git a/hw/dma/i82374.c b/hw/dma/i82374.c
> > >> index 6c0f975df0..5275d822e0 100644
> > >> --- a/hw/dma/i82374.c
> > >> +++ b/hw/dma/i82374.c
> > >> @@ -139,6 +139,7 @@ static void i82374_class_init(ObjectClass *klass, void *data)
> > >>      dc->realize = i82374_realize;
> > >>      dc->vmsd = &vmstate_i82374;
> > >>      dc->props = i82374_properties;
> > >> +    dc->user_creatable = false;
> > >
> > > A "Reason:" comment explaining why user_creatable=false is
> > > mandatory.  See the comment above user_creatable declaration in
> > > qdev-core.h for reference.
> > >
> > > I suggest the following:
> > >
> > >     /*
> > >      * Reason: i82374_realize() crashes (assertion failure inside isa_bus_dma()
> > >      *         if the device is instantiated twice.
> > >      */

I agree with the comment above. If there's nothing left to fix/add
I'll just send a v2 for this shortly.

> > 
> > We need to find out *why* it crashes.  Once we know, we can likely write
> > a better comment.
> 
> It crashes because isa_bus_dma() isn't supposed to be called
> twice for the same bus.
> 
> Making isa_bus_dma()/DMA_init()/i82374_realize() return an error
> instead of asserting would be even better than setting
> user_creatable=false.
> 
> -- 
> Eduardo
> 

-- 
Eduardo Otubo
Senior Software Engineer @ RedHat