Reqeust export symbol for API in arch/arm64/*

Reqeust export symbol for API in arch/arm64/*

[최동혁/DONGHYEOK CHOE]

Hello,

I am software engineer in charge of BSP (Samsung SOC vendor).

Recently, Google introduced GKI from Android R version.
We cannot use mainline API without 'export symbol' by the GKI policy.
But we want to make an arm64 specific vendor driver in {kernel source
root}/drivers/soc/samsung/*.

Could you support us to use the below APIs?

1. [register_kernel_break_hook]
To make runtime debug feature. We need architecture support.(break hook)
It's an architecture specific function. After cpu execute specific
instruction, A function with a parameter which is the context at that
time(the executing specific instruction) is performed. I am trying to
restore the locked context by using this fuction with  the el3 trap for
debugging hardlockup core(s).

2. [dump_backtrace]
Although 'dump_stack' is already supported, we need 'dump_backtrace' also.
Because we need lighten api to debug system. In some situation like bus
hang(HW bug), dump_stack highly likely make a problem again while printing
debug information.

Re: Reqeust export symbol for API in arch/arm64/*

[Will Deacon]

On Wed, May 06, 2020 at 09:46:45PM +0900, �ֵ���/DONGHYEOK CHOE wrote:
> I am software engineer in charge of BSP (Samsung SOC vendor).
> 
> Recently, Google introduced GKI from Android R version.
> We cannot use mainline API without 'export symbol' by the GKI policy.
> But we want to make an arm64 specific vendor driver in {kernel source
> root}/drivers/soc/samsung/*.
> 
> Could you support us to use the below APIs?

Sorry, but as a general rule of thumb the kernel doesn't EXPORT symbols
that are not used by in-tree modules. You'll need to submit your drivers
along with the patches doing the exports if they are to be considered
for inclusion.

Thanks,

Will

RE: Reqeust export symbol for API in arch/arm64/*

[최동혁/DONGHYEOK CHOE]

> -----Original Message-----
> From: Will Deacon <will@kernel.org>
> Sent: Wednesday, May 6, 2020 9:53 PM
> To: �ֵ���/DONGHYEOK CHOE <d7271.choe@samsung.com>
> Cc: linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org;
> hosung0.kim@samsung.com; changki.kim@samsung.com; hajun.sung@samsung.com;
> gregkh@google.com; youngmin.nam@samsung.com
> Subject: Re: Reqeust export symbol for API in arch/arm64/*
> 
> On Wed, May 06, 2020 at 09:46:45PM +0900,  ֵ   /DONGHYEOK CHOE wrote:
> > I am software engineer in charge of BSP (Samsung SOC vendor).
> >
> > Recently, Google introduced GKI from Android R version.
> > We cannot use mainline API without 'export symbol' by the GKI policy.
> > But we want to make an arm64 specific vendor driver in {kernel source
> > root}/drivers/soc/samsung/*.
> >
> > Could you support us to use the below APIs?
> 
> Sorry, but as a general rule of thumb the kernel doesn't EXPORT symbols
> that are not used by in-tree modules. You'll need to submit your drivers
> along with the patches doing the exports if they are to be considered for
> inclusion.
> 
> Thanks,
> 
> Will

Thank you for your quick response.
I'll try.

Thanks