linux-kernel - Re: Question - check in runtime which architecture am I running on

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Message-ID: <20190611140725.GA28902@infradead.org>
Date:   Tue, 11 Jun 2019 07:07:25 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     Oded Gabbay <oded.gabbay@...il.com>
Cc:     linuxppc-dev@...abs.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Linux-Kernel@...r. Kernel. Org" <linux-kernel@...r.kernel.org>
Subject: Re: Question - check in runtime which architecture am I running on

On Tue, Jun 11, 2019 at 03:30:08PM +0300, Oded Gabbay wrote:
> Hello POWER developers,
> 
> I'm trying to find out if there is an internal kernel API so that a
> PCI driver can call it to check if its PCI device is running inside a
> POWER9 machine. Alternatively, if that's not available, if it is
> running on a machine with powerpc architecture.

Your driver has absolutely not business knowing this.

> 
> I need this information as my device (Goya AI accelerator)
> unfortunately needs a slightly different configuration of its PCIe
> controller in case of POWER9 (need to set bit 59 to be 1 in all
> outbound transactions).

No, it doesn't.  You can query the output from dma_get_required_mask
to optimize for the DMA addresses you get, and otherwise you simply
set the maximum dma mask you support.  That is about the control you
get, and nothing else is a drivers business.