linux-kernel - Re: [PATCH v2] xen/events: Always allocate legacy interrupts on PV guests

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Date:	Fri, 20 Nov 2015 10:42:05 -0500
From:	Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:	Stefano Stabellini <stefano.stabellini@...citrix.com>
Cc:	konrad.wilk@...cle.com, david.vrabel@...rix.com,
	linux@....linux.org.uk, stefano.stabellini@...rix.com,
	jgross@...e.com, tglx@...utronix.de, vkuznets@...hat.com,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	xen-devel@...ts.xen.org, Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>
Subject: Re: [PATCH v2] xen/events: Always allocate legacy interrupts on PV
 guests

On 11/20/2015 10:36 AM, Stefano Stabellini wrote:
> On Fri, 20 Nov 2015, Boris Ostrovsky wrote:
>> On 11/20/2015 06:24 AM, Stefano Stabellini wrote:
>>> On Wed, 18 Nov 2015, Boris Ostrovsky wrote:
>>>> After commit 8c058b0b9c34 ("x86/irq: Probe for PIC presence before
>>>> allocating descs for legacy IRQs") early_irq_init() will no longer
>>>> preallocate descriptors for legacy interrupts if PIC does not
>>>> exist, which is the case for Xen PV guests.
>>>>
>>>> Therefore we may need to allocate those descriptors ourselves.
>>>>
>>>> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
>>>> Suggested-by: Thomas Gleixner <tglx@...utronix.de>
>>> You need to do this for arm64 too.
>>>
>>> FYI you can download arm64 cross-compilers from
>>> https://releases.linaro.org/14.04/components/toolchain/binaries/
>>> then you can use them by exporting ARCH=arm64 and
>>> CROSS_COMPILE=/path/to/gcc-linaro-aarch64-linux-gnu-version/bin/aarch64-linux-gnu-
>> I did test on arm but didn't realize that arm64 uses different include files.
>>
>> Does arm64 not have any legacy interrupts?
>>
>> BTW, I got this build error:
>>
>>    STUBCPY drivers/firmware/efi/libstub/lib-sort.stub.o
>> 0000000000000000 R_AARCH64_ABS64   __efistub_sort
>> 0000000000000008 R_AARCH64_ABS64   .init__ksymtab_strings
>> drivers/firmware/efi/libstub/lib-sort.stub.o: absolute symbol references not
>> allowed in the EFI stub
>> drivers/firmware/efi/libstub/Makefile:63: recipe for target
>> 'drivers/firmware/efi/libstub/lib-sort.stub.o' failed
>> make[4]: *** [drivers/firmware/efi/libstub/lib-sort.stub.o] Error 1
>> scripts/Makefile.build:403: recipe for target 'drivers/firmware/efi/libstub'
>> failed
>> make[3]: *** [drivers/firmware/efi/libstub] Error 2
>> scripts/Makefile.build:403: recipe for target 'drivers/firmware/efi' failed
>> make[2]: *** [drivers/firmware/efi] Error 2
>> scripts/Makefile.build:403: recipe for target 'drivers/firmware' failed
>> make[1]: *** [drivers/firmware] Error 2
>> Makefile:943: recipe for target 'drivers' failed
>> make: *** [drivers] Error 2
>>
>> I worked around this by removing some of EFI config options but presumably
>> this needs to be properly fixed.
> Interesting. This build error could be something new. Could you please
> post your kernel config?

Attached.

This, BTW, is on a relatively old toolstack:
gcc version 4.8.2 20131014 (prerelease) (crosstool-NG 
linaro-1.13.1-4.8-2013.10 - Linaro GCC 2013.10)

-boris

View attachment "xen-config.arm64.bad" of type "text/plain" (54506 bytes)