Re: [PATCH 04/16] iommu/amd: Check if IOAPIC information is correct

[Konrad Rzeszutek Wilk <konrad.wilk-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

On Fri, Sep 28, 2012 at 02:23:54PM +0200, Joerg Roedel wrote:
> When the IOAPIC information provided in the IVRS table is
> not correct or not complete the system may not boot at all
> when interrupt remapping is enabled. So check if this
> information is correct and print out a firmware bug message
> when it is not.
> 
> Signed-off-by: Joerg Roedel <joerg.roedel-5C7GfCeVMHo@public.gmane.org>
> ---
>  drivers/iommu/Kconfig          |    2 +-
>  drivers/iommu/amd_iommu_init.c |   27 ++++++++++++++++++++++++---
>  2 files changed, 25 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index 9f69b56..e39f9db 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -42,7 +42,7 @@ config AMD_IOMMU
>  	select PCI_PRI
>  	select PCI_PASID
>  	select IOMMU_API
> -	depends on X86_64 && PCI && ACPI
> +	depends on X86_64 && PCI && ACPI && X86_IO_APIC
>  	---help---
>  	  With this option you can enable support for AMD IOMMU hardware in
>  	  your system. An IOMMU is a hardware component which provides
> diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
> index db100c5..3f0b68f 100644
> --- a/drivers/iommu/amd_iommu_init.c
> +++ b/drivers/iommu/amd_iommu_init.c
> @@ -33,6 +33,7 @@
>  #include <asm/gart.h>
>  #include <asm/x86_init.h>
>  #include <asm/iommu_table.h>
> +#include <asm/io_apic.h>
>  
>  #include "amd_iommu_proto.h"
>  #include "amd_iommu_types.h"
> @@ -1572,6 +1573,23 @@ static void __init free_on_init_error(void)
>  #endif
>  }
>  
> +static bool __init check_ioapic_information(void)
> +{
> +	int idx;
> +
> +	for (idx = 0; idx < nr_ioapics; ++idx) {

That ++idx looks odd - and it looks like the file has a combination of
i++ and ++i. Any particular reason for using this particular one instead
of the more common: "idx++" ? Or just habit?