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SubjectRe: [PATCH linux-next] iommu: Enable LPAE pagetable on ARM only
From
On Mon, Feb 23, 2015 at 5:52 PM, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
> On Sunday 22 February 2015 17:09:06 Vincent Stehlé wrote:
>> LPAE iommu page table makes sense only for ARM architecture. Add the
>> corresponding dependency in Kconfig.
>>
>> This fixes the following runtime warnings on PA-RISC architecture:
>
> I suppose this is caused by the selftest code ?
>
>> WARNING: at drivers/iommu/io-pgtable-arm.c:413
>> Modules linked in:
>> CPU: 0 PID: 1 Comm: swapper/0 Not tainted
>> 3.19.0-next-20150222-00002-gc420256 #2 task: 17ca0000 ti: 17ca8000 task.ti:
>> 17ca8000
>>
>> YZrvWESTHLNXBCVMcbcbcbcbOGFRQPDI
>> PSW: 00000000000001001111111100001111 Not tainted
>> r00-03 0004ff0f 0000001b 104871b0 17ca83c0
>> r04-07 00001000 00000000 00000000 00000000
>> r08-11 00000000 40001000 1013b36c 17ca8248
>> r12-15 00000080 17e712c0 00000000 17c5e100
>> r16-19 0000000c 105d8eb0 40001000 ffffffff
>> r20-23 00000000 00800020 1048717c 00000000
>> r24-27 00001000 00000000 00000009 10774ce0
>> r28-31 00000000 00000027 17ca8480 10486d44
>> sr00-03 00000000 00000000 00000000 00000000
>> sr04-07 00000000 00000000 00000000 00000000
>>
>> IASQ: 00000000 00000000 IAOQ: 10486df4 10486df8
>> IIR: 03ffe01f ISR: 00000000 IOR: 17c86e54
>> CPU: 0 CR30: 17ca8000 CR31: 00000002
>> ORIG_R28: 00000001
>> IAOQ[0]: __arm_lpae_unmap+0x144/0x4cc
>> IAOQ[1]: __arm_lpae_unmap+0x148/0x4cc
>> RP(r2): arm_lpae_unmap+0x34/0x6c
>> Backtrace:
>> [<104871b0>] arm_lpae_unmap+0x34/0x6c
>> [<10127944>] 0x10127944
>> [<10168ee0>] do_one_initcall+0x128/0x1dc
>> [<101028fc>] 0x101028fc
>> [<10161b48>] kernel_init+0x1c/0x118
>> [<1015d01c>] end_fault_vector+0x1c/0x24
>> [<101762ec>] save_stack_trace+0x28/0x60
>>
>> Signed-off-by: Vincent Stehlé <vincent.stehle@laposte.net>
>> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>> Cc: Will Deacon <will.deacon@arm.com>
>> ---
>>
>>
>> Hi,
>>
>> This can be seen with e.g. Linux next-20150222 on parisc with allmodconfig.
>>
>> Best regards,
>>
>> V.
>>
>>
>> drivers/iommu/Kconfig | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
>> index baa0d97..c73fd72 100644
>> --- a/drivers/iommu/Kconfig
>> +++ b/drivers/iommu/Kconfig
>> @@ -22,6 +22,7 @@ config IOMMU_IO_PGTABLE
>>
>> config IOMMU_IO_PGTABLE_LPAE
>> bool "ARMv7/v8 Long Descriptor Format"
>> + depends on ARM
>
> How about ARM || COMPILE_TEST ? It can still be useful to compile the module
> on other architectures.

COMPILE_TEST is meant for test-compiling drivers or subsystems that are not
useful on all platforms. IMHO COMPILE_TEST kernels are still supposed to boot
without ill effects.

Now, I understand the issue on PA-RISC is with the selftest, not with the actual
IOMMU_IO_PGTABLE_LPAE module? Then IOMMU_IO_PGTABLE_LPAE
can depend on ARM || COMPILE_TEST (|| ARM64, cfr. Laurent's later email).

But the selftest should protect itself against running on non-ARM, either
by making IOMMU_IO_PGTABLE_LPAE_SELFTEST depend on ARM(64)
(without "|| COMPILE_TEST"), or by adding a check to arm_lpae_do_selftests(),
to please all compile-testers.

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds


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