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SubjectRe: [PATCH v2] iommu/vt-d: Make DMAR_UNITS_SUPPORTED a config setting
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On 2022/6/14 04:57, Jerry Snitselaar wrote:
> On Thu, May 12, 2022 at 10:13:09AM -0500, Steve Wahl wrote:
>> To support up to 64 sockets with 10 DMAR units each (640), make the
>> value of DMAR_UNITS_SUPPORTED adjustable by a config variable,
>> CONFIG_DMAR_UNITS_SUPPORTED, and make it's default 1024 when MAXSMP is
>> set.
>>
>> If the available hardware exceeds DMAR_UNITS_SUPPORTED (previously set
>> to MAX_IO_APICS, or 128), it causes these messages: "DMAR: Failed to
>> allocate seq_id", "DMAR: Parse DMAR table failure.", and "x2apic: IRQ
>> remapping doesn't support X2APIC mode x2apic disabled"; and the system
>> fails to boot properly.
>>
>> Signed-off-by: Steve Wahl <steve.wahl@hpe.com>
>> ---
>>
>> Note that we could not find a reason for connecting
>> DMAR_UNITS_SUPPORTED to MAX_IO_APICS as was done previously. Perhaps
>> it seemed like the two would continue to match on earlier processors.
>> There doesn't appear to be kernel code that assumes that the value of
>> one is related to the other.
>>
>> v2: Make this value a config option, rather than a fixed constant. The default
>> values should match previous configuration except in the MAXSMP case. Keeping the
>> value at a power of two was requested by Kevin Tian.
>>
>> drivers/iommu/intel/Kconfig | 6 ++++++
>> include/linux/dmar.h | 6 +-----
>> 2 files changed, 7 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/iommu/intel/Kconfig b/drivers/iommu/intel/Kconfig
>> index 247d0f2d5fdf..fdbda77ac21e 100644
>> --- a/drivers/iommu/intel/Kconfig
>> +++ b/drivers/iommu/intel/Kconfig
>> @@ -9,6 +9,12 @@ config DMAR_PERF
>> config DMAR_DEBUG
>> bool
>>
>> +config DMAR_UNITS_SUPPORTED
>> + int "Number of DMA Remapping Units supported"
>
> Also, should there be a "depends on (X86 || IA64)" here?

Do you have any compilation errors or warnings?

Best regards,
baolu

>
>> + default 1024 if MAXSMP
>> + default 128 if X86_64
>> + default 64
>> +
>> config INTEL_IOMMU
>> bool "Support for Intel IOMMU using DMA Remapping Devices"
>> depends on PCI_MSI && ACPI && (X86 || IA64)
>> diff --git a/include/linux/dmar.h b/include/linux/dmar.h
>> index 45e903d84733..0c03c1845c23 100644
>> --- a/include/linux/dmar.h
>> +++ b/include/linux/dmar.h
>> @@ -18,11 +18,7 @@
>>
>> struct acpi_dmar_header;
>>
>> -#ifdef CONFIG_X86
>> -# define DMAR_UNITS_SUPPORTED MAX_IO_APICS
>> -#else
>> -# define DMAR_UNITS_SUPPORTED 64
>> -#endif
>> +#define DMAR_UNITS_SUPPORTED CONFIG_DMAR_UNITS_SUPPORTED
>>
>> /* DMAR Flags */
>> #define DMAR_INTR_REMAP 0x1
>> --
>> 2.26.2
>>
>

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