[PATCH] Fix section type conflict in arch/ia64/xen/xen_pv_ops.c

[PATCH] Fix section type conflict in arch/ia64/xen/xen_pv_ops.c

[Takashi Iwai]

__initdata and const cannot be always a happy pair, as gcc-4.3.3 gives
the compile errors like:

  arch/ia64/xen/xen_pv_ops.c:156: error: xen_init_ops causes a section type conflict
  arch/ia64/xen/xen_pv_ops.c:340: error: xen_iosapic_ops causes a section type conflict

This patch simply removes const from data with __initdata.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

---
diff --git a/arch/ia64/xen/xen_pv_ops.c b/arch/ia64/xen/xen_pv_ops.c
index 04cd123..5d491d9 100644
--- a/arch/ia64/xen/xen_pv_ops.c
+++ b/arch/ia64/xen/xen_pv_ops.c
@@ -153,7 +153,7 @@ xen_post_smp_prepare_boot_cpu(void)
 	xen_setup_vcpu_info_placement();
 }
 
-static const struct pv_init_ops xen_init_ops __initdata = {
+static struct pv_init_ops xen_init_ops __initdata = {
 	.banner = xen_banner,
 
 	.reserve_memory = xen_reserve_memory,
@@ -260,7 +260,7 @@ xen_intrin_local_irq_restore(unsigned long mask)
 		xen_rsm_i();
 }
 
-static const struct pv_cpu_ops xen_cpu_ops __initdata = {
+static struct pv_cpu_ops xen_cpu_ops __initdata = {
 	.fc		= xen_fc,
 	.thash		= xen_thash,
 	.get_cpuid	= xen_get_cpuid,
@@ -337,7 +337,7 @@ xen_iosapic_write(char __iomem *iosapic, unsigned int reg, u32 val)
 	HYPERVISOR_physdev_op(PHYSDEVOP_apic_write, &apic_op);
 }
 
-static const struct pv_iosapic_ops xen_iosapic_ops __initdata = {
+static struct pv_iosapic_ops xen_iosapic_ops __initdata = {
 	.pcat_compat_init = xen_pcat_compat_init,
 	.__get_irq_chip = xen_iosapic_get_irq_chip,
 

Re: [PATCH] Fix section type conflict in arch/ia64/xen/xen_pv_ops.c

[Jeremy Fitzhardinge]

Takashi Iwai wrote:
> __initdata and const cannot be always a happy pair, as gcc-4.3.3 gives
> the compile errors like:
>
>   arch/ia64/xen/xen_pv_ops.c:156: error: xen_init_ops causes a section type conflict
>   arch/ia64/xen/xen_pv_ops.c:340: error: xen_iosapic_ops causes a section type conflict
>
> This patch simply removes const from data with __initdata.
>   

Yeah, I've seen these sort of messages before, but I don't see why 
there's an inherent problem with having const __initdata.

Sam?

    J

> Signed-off-by: Takashi Iwai <tiwai@suse.de>
>
> ---
> diff --git a/arch/ia64/xen/xen_pv_ops.c b/arch/ia64/xen/xen_pv_ops.c
> index 04cd123..5d491d9 100644
> --- a/arch/ia64/xen/xen_pv_ops.c
> +++ b/arch/ia64/xen/xen_pv_ops.c
> @@ -153,7 +153,7 @@ xen_post_smp_prepare_boot_cpu(void)
>  	xen_setup_vcpu_info_placement();
>  }
>  
> -static const struct pv_init_ops xen_init_ops __initdata = {
> +static struct pv_init_ops xen_init_ops __initdata = {
>  	.banner = xen_banner,
>  
>  	.reserve_memory = xen_reserve_memory,
> @@ -260,7 +260,7 @@ xen_intrin_local_irq_restore(unsigned long mask)
>  		xen_rsm_i();
>  }
>  
> -static const struct pv_cpu_ops xen_cpu_ops __initdata = {
> +static struct pv_cpu_ops xen_cpu_ops __initdata = {
>  	.fc		= xen_fc,
>  	.thash		= xen_thash,
>  	.get_cpuid	= xen_get_cpuid,
> @@ -337,7 +337,7 @@ xen_iosapic_write(char __iomem *iosapic, unsigned int reg, u32 val)
>  	HYPERVISOR_physdev_op(PHYSDEVOP_apic_write, &apic_op);
>  }
>  
> -static const struct pv_iosapic_ops xen_iosapic_ops __initdata = {
> +static struct pv_iosapic_ops xen_iosapic_ops __initdata = {
>  	.pcat_compat_init = xen_pcat_compat_init,
>  	.__get_irq_chip = xen_iosapic_get_irq_chip,
>  
>   

Re: [PATCH] Fix section type conflict in arch/ia64/xen/xen_pv_ops.c

[Takashi Iwai]

At Thu, 06 Nov 2008 10:57:21 -0800,
Jeremy Fitzhardinge wrote:
> 
> Takashi Iwai wrote:
> > __initdata and const cannot be always a happy pair, as gcc-4.3.3 gives
> > the compile errors like:
> >
> >   arch/ia64/xen/xen_pv_ops.c:156: error: xen_init_ops causes a section type conflict
> >   arch/ia64/xen/xen_pv_ops.c:340: error: xen_iosapic_ops causes a section type conflict
> >
> > This patch simply removes const from data with __initdata.
> >   
> 
> Yeah, I've seen these sort of messages before, but I don't see why 
> there's an inherent problem with having const __initdata.

Oh, wait; just looking through linux/init.h, I see we have now
__initconst.  Maybe this is the right choice?

This would be better documented somewhere in Documentation/*...


thanks,

Takashi


> 
> Sam?
> 
>     J
> 
> > Signed-off-by: Takashi Iwai <tiwai@suse.de>
> >
> > ---
> > diff --git a/arch/ia64/xen/xen_pv_ops.c b/arch/ia64/xen/xen_pv_ops.c
> > index 04cd123..5d491d9 100644
> > --- a/arch/ia64/xen/xen_pv_ops.c
> > +++ b/arch/ia64/xen/xen_pv_ops.c
> > @@ -153,7 +153,7 @@ xen_post_smp_prepare_boot_cpu(void)
> >  	xen_setup_vcpu_info_placement();
> >  }
> >  
> > -static const struct pv_init_ops xen_init_ops __initdata = {
> > +static struct pv_init_ops xen_init_ops __initdata = {
> >  	.banner = xen_banner,
> >  
> >  	.reserve_memory = xen_reserve_memory,
> > @@ -260,7 +260,7 @@ xen_intrin_local_irq_restore(unsigned long mask)
> >  		xen_rsm_i();
> >  }
> >  
> > -static const struct pv_cpu_ops xen_cpu_ops __initdata = {
> > +static struct pv_cpu_ops xen_cpu_ops __initdata = {
> >  	.fc		= xen_fc,
> >  	.thash		= xen_thash,
> >  	.get_cpuid	= xen_get_cpuid,
> > @@ -337,7 +337,7 @@ xen_iosapic_write(char __iomem *iosapic, unsigned int reg, u32 val)
> >  	HYPERVISOR_physdev_op(PHYSDEVOP_apic_write, &apic_op);
> >  }
> >  
> > -static const struct pv_iosapic_ops xen_iosapic_ops __initdata = {
> > +static struct pv_iosapic_ops xen_iosapic_ops __initdata = {
> >  	.pcat_compat_init = xen_pcat_compat_init,
> >  	.__get_irq_chip = xen_iosapic_get_irq_chip,
> >  
> >   
> 

Re: [PATCH] Fix section type conflict in arch/ia64/xen/xen_pv_ops.c

[Sam Ravnborg]

On Thu, Nov 06, 2008 at 10:57:21AM -0800, Jeremy Fitzhardinge wrote:
> Takashi Iwai wrote:
> >__initdata and const cannot be always a happy pair, as gcc-4.3.3 gives
> >the compile errors like:
> >
> >  arch/ia64/xen/xen_pv_ops.c:156: error: xen_init_ops causes a section 
> >  type conflict
> >  arch/ia64/xen/xen_pv_ops.c:340: error: xen_iosapic_ops causes a section 
> >  type conflict
> >
> >This patch simply removes const from data with __initdata.
> >  
> 
> Yeah, I've seen these sort of messages before, but I don't see why 
> there's an inherent problem with having const __initdata.
> 
> Sam?

The root problem here is that in some cases gcc will stuff this into
a section marked CONST and in other cases not.
So when we manually specify the section we better not mix const and
non-const stuff in the same section.
The problem is that it is very gcc dependent. I have with powerpc
seen that the same code was not put in CONST with a 32 bit build,
but with the 64 bit build it was.
The only cure was to remove the const and use initdata.
You can try to play with initconst - and it may work.
But you need to have pretty good build coverage to be sure.

	Sam

Re: [PATCH] Fix section type conflict in arch/ia64/xen/xen_pv_ops.c

[Takashi Iwai]

At Thu, 6 Nov 2008 22:48:48 +0100,
Sam Ravnborg wrote:
> 
> On Thu, Nov 06, 2008 at 10:57:21AM -0800, Jeremy Fitzhardinge wrote:
> > Takashi Iwai wrote:
> > >__initdata and const cannot be always a happy pair, as gcc-4.3.3 gives
> > >the compile errors like:
> > >
> > >  arch/ia64/xen/xen_pv_ops.c:156: error: xen_init_ops causes a section 
> > >  type conflict
> > >  arch/ia64/xen/xen_pv_ops.c:340: error: xen_iosapic_ops causes a section 
> > >  type conflict
> > >
> > >This patch simply removes const from data with __initdata.
> > >  
> > 
> > Yeah, I've seen these sort of messages before, but I don't see why 
> > there's an inherent problem with having const __initdata.
> > 
> > Sam?
> 
> The root problem here is that in some cases gcc will stuff this into
> a section marked CONST and in other cases not.
> So when we manually specify the section we better not mix const and
> non-const stuff in the same section.
> The problem is that it is very gcc dependent. I have with powerpc
> seen that the same code was not put in CONST with a 32 bit build,
> but with the 64 bit build it was.
> The only cure was to remove the const and use initdata.
> You can try to play with initconst - and it may work.
> But you need to have pretty good build coverage to be sure.

OK, then my original patch should do right :)
Do you guys see any problems with it?

Right now 2.6.28-rc kernel doesn't build, thus this is basically a
regression.


thanks,

Takashi

Re: [PATCH] Fix section type conflict in arch/ia64/xen/xen_pv_ops.c

[Isaku Yamahata]

On Tue, Nov 11, 2008 at 08:51:11AM +0100, Takashi Iwai wrote:
> At Thu, 6 Nov 2008 22:48:48 +0100,
> Sam Ravnborg wrote:
> > 
> > On Thu, Nov 06, 2008 at 10:57:21AM -0800, Jeremy Fitzhardinge wrote:
> > > Takashi Iwai wrote:
> > > >__initdata and const cannot be always a happy pair, as gcc-4.3.3 gives
> > > >the compile errors like:
> > > >
> > > >  arch/ia64/xen/xen_pv_ops.c:156: error: xen_init_ops causes a section 
> > > >  type conflict
> > > >  arch/ia64/xen/xen_pv_ops.c:340: error: xen_iosapic_ops causes a section 
> > > >  type conflict
> > > >
> > > >This patch simply removes const from data with __initdata.
> > > >  
> > > 
> > > Yeah, I've seen these sort of messages before, but I don't see why 
> > > there's an inherent problem with having const __initdata.
> > > 
> > > Sam?
> > 
> > The root problem here is that in some cases gcc will stuff this into
> > a section marked CONST and in other cases not.
> > So when we manually specify the section we better not mix const and
> > non-const stuff in the same section.
> > The problem is that it is very gcc dependent. I have with powerpc
> > seen that the same code was not put in CONST with a 32 bit build,
> > but with the 64 bit build it was.
> > The only cure was to remove the const and use initdata.
> > You can try to play with initconst - and it may work.
> > But you need to have pretty good build coverage to be sure.
> 
> OK, then my original patch should do right :)
> Do you guys see any problems with it?
> 
> Right now 2.6.28-rc kernel doesn't build, thus this is basically a
> regression.

I'm fine with the patch.

The above sounds x86 xen potentially has the same issue, though.

linux-2.6/arch/x86/xen $ grep __initdata *
enlighten.c:static const struct pv_info xen_info __initdata = {
enlighten.c:static const struct pv_init_ops xen_init_ops __initdata = {
enlighten.c:static const struct pv_time_ops xen_time_ops __initdata = {
enlighten.c:static const struct pv_cpu_ops xen_cpu_ops __initdata = {
enlighten.c:static const struct pv_apic_ops xen_apic_ops __initdata = {
enlighten.c:static const struct pv_mmu_ops xen_mmu_ops __initdata = {
enlighten.c:static const struct machine_ops __initdata xen_machine_ops = {
irq.c:static const struct pv_irq_ops xen_irq_ops __initdata = {
smp.c:static const struct smp_ops xen_smp_ops __initdata = {

thanks,
-- 
yamahata

Re: [PATCH] Fix section type conflict in arch/ia64/xen/xen_pv_ops.c

[Takashi Iwai]

At Tue, 11 Nov 2008 17:15:52 +0900,
Isaku Yamahata wrote:
> 
> On Tue, Nov 11, 2008 at 08:51:11AM +0100, Takashi Iwai wrote:
> > At Thu, 6 Nov 2008 22:48:48 +0100,
> > Sam Ravnborg wrote:
> > > 
> > > On Thu, Nov 06, 2008 at 10:57:21AM -0800, Jeremy Fitzhardinge wrote:
> > > > Takashi Iwai wrote:
> > > > >__initdata and const cannot be always a happy pair, as gcc-4.3.3 gives
> > > > >the compile errors like:
> > > > >
> > > > >  arch/ia64/xen/xen_pv_ops.c:156: error: xen_init_ops causes a section 
> > > > >  type conflict
> > > > >  arch/ia64/xen/xen_pv_ops.c:340: error: xen_iosapic_ops causes a section 
> > > > >  type conflict
> > > > >
> > > > >This patch simply removes const from data with __initdata.
> > > > >  
> > > > 
> > > > Yeah, I've seen these sort of messages before, but I don't see why 
> > > > there's an inherent problem with having const __initdata.
> > > > 
> > > > Sam?
> > > 
> > > The root problem here is that in some cases gcc will stuff this into
> > > a section marked CONST and in other cases not.
> > > So when we manually specify the section we better not mix const and
> > > non-const stuff in the same section.
> > > The problem is that it is very gcc dependent. I have with powerpc
> > > seen that the same code was not put in CONST with a 32 bit build,
> > > but with the 64 bit build it was.
> > > The only cure was to remove the const and use initdata.
> > > You can try to play with initconst - and it may work.
> > > But you need to have pretty good build coverage to be sure.
> > 
> > OK, then my original patch should do right :)
> > Do you guys see any problems with it?
> > 
> > Right now 2.6.28-rc kernel doesn't build, thus this is basically a
> > regression.
> 
> I'm fine with the patch.
> 
> The above sounds x86 xen potentially has the same issue, though.
> 
> linux-2.6/arch/x86/xen $ grep __initdata *
> enlighten.c:static const struct pv_info xen_info __initdata = {
> enlighten.c:static const struct pv_init_ops xen_init_ops __initdata = {
> enlighten.c:static const struct pv_time_ops xen_time_ops __initdata = {
> enlighten.c:static const struct pv_cpu_ops xen_cpu_ops __initdata = {
> enlighten.c:static const struct pv_apic_ops xen_apic_ops __initdata = {
> enlighten.c:static const struct pv_mmu_ops xen_mmu_ops __initdata = {
> enlighten.c:static const struct machine_ops __initdata xen_machine_ops = {
> irq.c:static const struct pv_irq_ops xen_irq_ops __initdata = {
> smp.c:static const struct smp_ops xen_smp_ops __initdata = {

Oh, care to create a patch?


thanks,

Takashi

Re: [PATCH] Fix section type conflict in arch/ia64/xen/xen_pv_ops.c

[Isaku Yamahata]

On Tue, Nov 11, 2008 at 09:18:50AM +0100, Takashi Iwai wrote:
> At Tue, 11 Nov 2008 17:15:52 +0900,
> Isaku Yamahata wrote:
> > 
> > On Tue, Nov 11, 2008 at 08:51:11AM +0100, Takashi Iwai wrote:
> > > At Thu, 6 Nov 2008 22:48:48 +0100,
> > > Sam Ravnborg wrote:
> > > > 
> > > > On Thu, Nov 06, 2008 at 10:57:21AM -0800, Jeremy Fitzhardinge wrote:
> > > > > Takashi Iwai wrote:
> > > > > >__initdata and const cannot be always a happy pair, as gcc-4.3.3 gives
> > > > > >the compile errors like:
> > > > > >
> > > > > >  arch/ia64/xen/xen_pv_ops.c:156: error: xen_init_ops causes a section 
> > > > > >  type conflict
> > > > > >  arch/ia64/xen/xen_pv_ops.c:340: error: xen_iosapic_ops causes a section 
> > > > > >  type conflict
> > > > > >
> > > > > >This patch simply removes const from data with __initdata.
> > > > > >  
> > > > > 
> > > > > Yeah, I've seen these sort of messages before, but I don't see why 
> > > > > there's an inherent problem with having const __initdata.
> > > > > 
> > > > > Sam?
> > > > 
> > > > The root problem here is that in some cases gcc will stuff this into
> > > > a section marked CONST and in other cases not.
> > > > So when we manually specify the section we better not mix const and
> > > > non-const stuff in the same section.
> > > > The problem is that it is very gcc dependent. I have with powerpc
> > > > seen that the same code was not put in CONST with a 32 bit build,
> > > > but with the 64 bit build it was.
> > > > The only cure was to remove the const and use initdata.
> > > > You can try to play with initconst - and it may work.
> > > > But you need to have pretty good build coverage to be sure.
> > > 
> > > OK, then my original patch should do right :)
> > > Do you guys see any problems with it?
> > > 
> > > Right now 2.6.28-rc kernel doesn't build, thus this is basically a
> > > regression.
> > 
> > I'm fine with the patch.
> > 
> > The above sounds x86 xen potentially has the same issue, though.
> > 
> > linux-2.6/arch/x86/xen $ grep __initdata *
> > enlighten.c:static const struct pv_info xen_info __initdata = {
> > enlighten.c:static const struct pv_init_ops xen_init_ops __initdata = {
> > enlighten.c:static const struct pv_time_ops xen_time_ops __initdata = {
> > enlighten.c:static const struct pv_cpu_ops xen_cpu_ops __initdata = {
> > enlighten.c:static const struct pv_apic_ops xen_apic_ops __initdata = {
> > enlighten.c:static const struct pv_mmu_ops xen_mmu_ops __initdata = {
> > enlighten.c:static const struct machine_ops __initdata xen_machine_ops = {
> > irq.c:static const struct pv_irq_ops xen_irq_ops __initdata = {
> > smp.c:static const struct smp_ops xen_smp_ops __initdata = {
> 
> Oh, care to create a patch?

Here is.

__initdata and const cannot be always a happy pair and
x86 xen has the potential issue.
This patch simply removes const from data with __initdata
under arch/x86/xen/.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 0013a72..19f758c 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1173,14 +1173,14 @@ static void xen_set_fixmap(unsigned idx, unsigned long phys, pgprot_t prot)
 #endif
 }
 
-static const struct pv_info xen_info __initdata = {
+static struct pv_info xen_info __initdata = {
 	.paravirt_enabled = 1,
 	.shared_kernel_pmd = 0,
 
 	.name = "Xen",
 };
 
-static const struct pv_init_ops xen_init_ops __initdata = {
+static struct pv_init_ops xen_init_ops __initdata = {
 	.patch = xen_patch,
 
 	.banner = xen_banner,
@@ -1189,7 +1189,7 @@ static const struct pv_init_ops xen_init_ops __initdata = {
 	.post_allocator_init = xen_post_allocator_init,
 };
 
-static const struct pv_time_ops xen_time_ops __initdata = {
+static struct pv_time_ops xen_time_ops __initdata = {
 	.time_init = xen_time_init,
 
 	.set_wallclock = xen_set_wallclock,
@@ -1198,7 +1198,7 @@ static const struct pv_time_ops xen_time_ops __initdata = {
 	.sched_clock = xen_sched_clock,
 };
 
-static const struct pv_cpu_ops xen_cpu_ops __initdata = {
+static struct pv_cpu_ops xen_cpu_ops __initdata = {
 	.cpuid = xen_cpuid,
 
 	.set_debugreg = xen_set_debugreg,
@@ -1260,7 +1260,7 @@ static const struct pv_cpu_ops xen_cpu_ops __initdata = {
 	},
 };
 
-static const struct pv_apic_ops xen_apic_ops __initdata = {
+static struct pv_apic_ops xen_apic_ops __initdata = {
 #ifdef CONFIG_X86_LOCAL_APIC
 	.setup_boot_clock = paravirt_nop,
 	.setup_secondary_clock = paravirt_nop,
@@ -1268,7 +1268,7 @@ static const struct pv_apic_ops xen_apic_ops __initdata = {
 #endif
 };
 
-static const struct pv_mmu_ops xen_mmu_ops __initdata = {
+static struct pv_mmu_ops xen_mmu_ops __initdata = {
 	.pagetable_setup_start = xen_pagetable_setup_start,
 	.pagetable_setup_done = xen_pagetable_setup_done,
 
@@ -1381,7 +1381,7 @@ static void xen_crash_shutdown(struct pt_regs *regs)
 	xen_reboot(SHUTDOWN_crash);
 }
 
-static const struct machine_ops __initdata xen_machine_ops = {
+static struct machine_ops __initdata xen_machine_ops = {
 	.restart = xen_restart,
 	.halt = xen_machine_halt,
 	.power_off = xen_machine_halt,
diff --git a/arch/x86/xen/irq.c b/arch/x86/xen/irq.c
index 28b85ab..ffadf3a 100644
--- a/arch/x86/xen/irq.c
+++ b/arch/x86/xen/irq.c
@@ -124,7 +124,7 @@ static void xen_halt(void)
 		xen_safe_halt();
 }
 
-static const struct pv_irq_ops xen_irq_ops __initdata = {
+static struct pv_irq_ops xen_irq_ops __initdata = {
 	.init_IRQ = __xen_init_IRQ,
 	.save_fl = xen_save_fl,
 	.restore_fl = xen_restore_fl,
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index d77da61..f0a1ea3 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -466,7 +466,7 @@ static irqreturn_t xen_call_function_single_interrupt(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-static const struct smp_ops xen_smp_ops __initdata = {
+static struct smp_ops xen_smp_ops __initdata = {
 	.smp_prepare_boot_cpu = xen_smp_prepare_boot_cpu,
 	.smp_prepare_cpus = xen_smp_prepare_cpus,
 	.smp_cpus_done = xen_smp_cpus_done,


-- 
yamahata

Re: [PATCH] Fix section type conflict in arch/ia64/xen/xen_pv_ops.c

[Jeremy Fitzhardinge]

Isaku Yamahata wrote:
> Here is.
>
> __initdata and const cannot be always a happy pair and
> x86 xen has the potential issue.
> This patch simply removes const from data with __initdata
> under arch/x86/xen/.
>   

No, I think the proper fix is to use __initconst.

    J

Re: [PATCH] Fix section type conflict in arch/ia64/xen/xen_pv_ops.c

[Takashi Iwai]

At Tue, 11 Nov 2008 09:43:27 -0800,
Jeremy Fitzhardinge wrote:
> 
> Isaku Yamahata wrote:
> > Here is.
> >
> > __initdata and const cannot be always a happy pair and
> > x86 xen has the potential issue.
> > This patch simply removes const from data with __initdata
> > under arch/x86/xen/.
> >   
> 
> No, I think the proper fix is to use __initconst.

The problem is that it depends on gcc version which section it goes.
Thus __initconst could break some gcc versions as well.


Takashi

Re: [PATCH] Fix section type conflict in arch/ia64/xen/xen_pv_ops.c

[Jeremy Fitzhardinge]

Takashi Iwai wrote:
> At Tue, 11 Nov 2008 09:43:27 -0800,
> Jeremy Fitzhardinge wrote:
>   
>> Isaku Yamahata wrote:
>>     
>>> Here is.
>>>
>>> __initdata and const cannot be always a happy pair and
>>> x86 xen has the potential issue.
>>> This patch simply removes const from data with __initdata
>>> under arch/x86/xen/.
>>>   
>>>       
>> No, I think the proper fix is to use __initconst.
>>     
>
> The problem is that it depends on gcc version which section it goes.
> Thus __initconst could break some gcc versions as well.
>   

Why?  __initconst explicitly puts it in .init.rodata.

    J

Re: [PATCH] Fix section type conflict in arch/ia64/xen/xen_pv_ops.c

[Takashi Iwai]

At Tue, 11 Nov 2008 10:47:24 -0800,
Jeremy Fitzhardinge wrote:
> 
> Takashi Iwai wrote:
> > At Tue, 11 Nov 2008 09:43:27 -0800,
> > Jeremy Fitzhardinge wrote:
> >   
> >> Isaku Yamahata wrote:
> >>     
> >>> Here is.
> >>>
> >>> __initdata and const cannot be always a happy pair and
> >>> x86 xen has the potential issue.
> >>> This patch simply removes const from data with __initdata
> >>> under arch/x86/xen/.
> >>>   
> >>>       
> >> No, I think the proper fix is to use __initconst.
> >>     
> >
> > The problem is that it depends on gcc version which section it goes.
> > Thus __initconst could break some gcc versions as well.
> >   
> 
> Why?  __initconst explicitly puts it in .init.rodata.

Hrm, right, that's what __initconst does.  Just confused.
Then I'm wondering in which case __initconst can be broken...
Sam?  Do you have any particular reports?


Takashi

Re: [PATCH] Fix section type conflict in arch/ia64/xen/xen_pv_ops.c

[Sam Ravnborg]

On Tue, Nov 11, 2008 at 08:04:30PM +0100, Takashi Iwai wrote:
> At Tue, 11 Nov 2008 10:47:24 -0800,
> Jeremy Fitzhardinge wrote:
> > 
> > Takashi Iwai wrote:
> > > At Tue, 11 Nov 2008 09:43:27 -0800,
> > > Jeremy Fitzhardinge wrote:
> > >   
> > >> Isaku Yamahata wrote:
> > >>     
> > >>> Here is.
> > >>>
> > >>> __initdata and const cannot be always a happy pair and
> > >>> x86 xen has the potential issue.
> > >>> This patch simply removes const from data with __initdata
> > >>> under arch/x86/xen/.
> > >>>   
> > >>>       
> > >> No, I think the proper fix is to use __initconst.
> > >>     
> > >
> > > The problem is that it depends on gcc version which section it goes.
> > > Thus __initconst could break some gcc versions as well.
> > >   
> > 
> > Why?  __initconst explicitly puts it in .init.rodata.
> 
> Hrm, right, that's what __initconst does.  Just confused.
> Then I'm wondering in which case __initconst can be broken...
> Sam?  Do you have any particular reports?

I have only got reports that __initconst causes gcc build failure
on powerpc 64 bit.
So for x86 it should be safe to use __initconst.

	Sam