Compilation Error in extras/mini-os/tpmback.c

Compilation Error in extras/mini-os/tpmback.c

[Dushyant Behl]

Hi,

I'm trying to compile xen from the source and i'm getting this
compilation error while running a make world.

tpmback.c: In function ‘tpmif_change_state’:
tpmback.c:350:4: error: format ‘%d’ expects argument of type ‘int *’,
but argument 3 has type ‘enum xenbus_state *’ [-Werror=format=]
    if(sscanf(value, "%d", &readst) != 1) {
    ^
cc1: all warnings being treated as errors
make[3]: *** [/home/corvo/gsoc/code/xen/stubdom/mini-os-x86_64-vtpm/tpmback.o]
Error 1

Could anyone explain that if this is just problem on my side or this
is not fixed in the git tree.

Thanks and Regards,
Dushyant

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Re: Compilation Error in extras/mini-os/tpmback.c

[Ian Campbell]

On Wed, 2014-07-16 at 11:25 +0530, Dushyant Behl wrote:
> Hi,
> 
> I'm trying to compile xen from the source and i'm getting this
> compilation error while running a make world.
> 
> tpmback.c: In function ‘tpmif_change_state’:
> tpmback.c:350:4: error: format ‘%d’ expects argument of type ‘int *’,
> but argument 3 has type ‘enum xenbus_state *’ [-Werror=format=]
>     if(sscanf(value, "%d", &readst) != 1) {
>     ^
> cc1: all warnings being treated as errors
> make[3]: *** [/home/corvo/gsoc/code/xen/stubdom/mini-os-x86_64-vtpm/tpmback.o]
> Error 1
> 
> Could anyone explain that if this is just problem on my side or this
> is not fixed in the git tree.

It looks like a legitimate issue to me. I expect you are just the first
person to use a compiler which picks up in this particular issue.

I'm not sure what the correct fix is since C doesn't mandate very much
about the storage size of an enum, so casting is probably not the right
answer.

Probably the value needs to be read into an actual int variable and then
assigned to the enum. Perhaps Ian J (Ccd) knows what the right thing to
do is.

Also CCing the mini-os and tpmback maintainers...

Ian.


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Re: Compilation Error in extras/mini-os/tpmback.c

[Samuel Thibault]

Ian Campbell, le Wed 16 Jul 2014 10:13:31 +0100, a écrit :
> On Wed, 2014-07-16 at 11:25 +0530, Dushyant Behl wrote:
> > I'm trying to compile xen from the source and i'm getting this
> > compilation error while running a make world.
> > 
> > tpmback.c: In function ‘tpmif_change_state’:
> > tpmback.c:350:4: error: format ‘%d’ expects argument of type ‘int *’,
> > but argument 3 has type ‘enum xenbus_state *’ [-Werror=format=]
> >     if(sscanf(value, "%d", &readst) != 1) {
> >     ^
> > cc1: all warnings being treated as errors
> > make[3]: *** [/home/corvo/gsoc/code/xen/stubdom/mini-os-x86_64-vtpm/tpmback.o]
> > Error 1
> > 
> > Could anyone explain that if this is just problem on my side or this
> > is not fixed in the git tree.
> 
> It looks like a legitimate issue to me. I expect you are just the first
> person to use a compiler which picks up in this particular issue.
> 
> I'm not sure what the correct fix is since C doesn't mandate very much
> about the storage size of an enum, so casting is probably not the right
> answer.

Indeed, C99 apparently says “The choice of type is
implementation-defined”, so

> Probably the value needs to be read into an actual int variable and then
> assigned to the enum.

that seems like the proper solution.

Samuel

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Re: Compilation Error in extras/mini-os/tpmback.c

[Ian Campbell]

On Thu, 2014-07-17 at 20:21 +0200, Samuel Thibault wrote:
> Ian Campbell, le Wed 16 Jul 2014 10:13:31 +0100, a écrit :
> > On Wed, 2014-07-16 at 11:25 +0530, Dushyant Behl wrote:
> > > I'm trying to compile xen from the source and i'm getting this
> > > compilation error while running a make world.
> > > 
> > > tpmback.c: In function ‘tpmif_change_state’:
> > > tpmback.c:350:4: error: format ‘%d’ expects argument of type ‘int *’,
> > > but argument 3 has type ‘enum xenbus_state *’ [-Werror=format=]
> > >     if(sscanf(value, "%d", &readst) != 1) {
> > >     ^
> > > cc1: all warnings being treated as errors
> > > make[3]: *** [/home/corvo/gsoc/code/xen/stubdom/mini-os-x86_64-vtpm/tpmback.o]
> > > Error 1
> > > 
> > > Could anyone explain that if this is just problem on my side or this
> > > is not fixed in the git tree.
> > 
> > It looks like a legitimate issue to me. I expect you are just the first
> > person to use a compiler which picks up in this particular issue.
> > 
> > I'm not sure what the correct fix is since C doesn't mandate very much
> > about the storage size of an enum, so casting is probably not the right
> > answer.
> 
> Indeed, C99 apparently says “The choice of type is
> implementation-defined”, so
> 
> > Probably the value needs to be read into an actual int variable and then
> > assigned to the enum.
> 
> that seems like the proper solution.

Great. Dushyant, are you able to rustle up a patch?

http://wiki.xen.org/wiki/Submitting_Xen_Patches has some guidance on the
procedure.

Ian.


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Re: Compilation Error in extras/mini-os/tpmback.c

[Dushyant Behl]

Sure, I'll be happy to do it.

On Fri, Jul 18, 2014 at 3:25 PM, Ian Campbell <Ian.Campbell@citrix.com> wrote:
> On Thu, 2014-07-17 at 20:21 +0200, Samuel Thibault wrote:
>> Ian Campbell, le Wed 16 Jul 2014 10:13:31 +0100, a écrit :
>> > On Wed, 2014-07-16 at 11:25 +0530, Dushyant Behl wrote:
>> > > I'm trying to compile xen from the source and i'm getting this
>> > > compilation error while running a make world.
>> > >
>> > > tpmback.c: In function ‘tpmif_change_state’:
>> > > tpmback.c:350:4: error: format ‘%d’ expects argument of type ‘int *’,
>> > > but argument 3 has type ‘enum xenbus_state *’ [-Werror=format=]
>> > >     if(sscanf(value, "%d", &readst) != 1) {
>> > >     ^
>> > > cc1: all warnings being treated as errors
>> > > make[3]: *** [/home/corvo/gsoc/code/xen/stubdom/mini-os-x86_64-vtpm/tpmback.o]
>> > > Error 1
>> > >
>> > > Could anyone explain that if this is just problem on my side or this
>> > > is not fixed in the git tree.
>> >
>> > It looks like a legitimate issue to me. I expect you are just the first
>> > person to use a compiler which picks up in this particular issue.
>> >
>> > I'm not sure what the correct fix is since C doesn't mandate very much
>> > about the storage size of an enum, so casting is probably not the right
>> > answer.
>>
>> Indeed, C99 apparently says “The choice of type is
>> implementation-defined”, so
>>
>> > Probably the value needs to be read into an actual int variable and then
>> > assigned to the enum.
>>
>> that seems like the proper solution.
>
> Great. Dushyant, are you able to rustle up a patch?
>
> http://wiki.xen.org/wiki/Submitting_Xen_Patches has some guidance on the
> procedure.
>
> Ian.
>

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Re: Compilation Error in extras/mini-os/tpmback.c

[Ian Campbell]

On Fri, 2014-07-18 at 15:31 +0530, Dushyant Behl wrote:
> Sure, I'll be happy to do it.

THanks!