linux-kernel - Re: [PATCH] drm/ttm: provide default page protection for UML

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Message-ID: <9faacbc8-3346-8033-5b4d-60543eae959e@cambridgegreys.com>
Date:   Thu, 2 Sep 2021 06:48:43 +0100
From:   Anton Ivanov <anton.ivanov@...bridgegreys.com>
To:     Randy Dunlap <rdunlap@...radead.org>, linux-kernel@...r.kernel.org
Cc:     Thomas Hellström 
        <thomas.hellstrom@...ux.intel.com>,
        Christian König <christian.koenig@....com>,
        Huang Rui <ray.huang@....com>, dri-devel@...ts.freedesktop.org,
        Jeff Dike <jdike@...toit.com>,
        Richard Weinberger <richard@....at>,
        linux-um@...ts.infradead.org, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>
Subject: Re: [PATCH] drm/ttm: provide default page protection for UML

On 02/09/2021 03:01, Randy Dunlap wrote:
> boot_cpu_data [struct cpuinfo_um (on UML)] does not have a struct
> member named 'x86', so provide a default page protection mode
> for CONFIG_UML.
> 
> Mends this build error:
> ../drivers/gpu/drm/ttm/ttm_module.c: In function ‘ttm_prot_from_caching’:
> ../drivers/gpu/drm/ttm/ttm_module.c:59:24: error: ‘struct cpuinfo_um’ has no member named ‘x86’
>    else if (boot_cpu_data.x86 > 3)
>                          ^
> 
> Fixes: 3bf3710e3718 ("drm/ttm: Add a generic TTM memcpy move for page-based iomem")
> Signed-off-by: Randy Dunlap <rdunlap@...radead.org>
> Cc: Thomas Hellström <thomas.hellstrom@...ux.intel.com>
> Cc: Christian König <christian.koenig@....com>
> Cc: Huang Rui <ray.huang@....com>
> Cc: dri-devel@...ts.freedesktop.org
> Cc: Jeff Dike <jdike@...toit.com>
> Cc: Richard Weinberger <richard@....at>
> Cc: Anton Ivanov <anton.ivanov@...bridgegreys.com>
> Cc: linux-um@...ts.infradead.org
> Cc: David Airlie <airlied@...ux.ie>
> Cc: Daniel Vetter <daniel@...ll.ch>
> ---
>   drivers/gpu/drm/ttm/ttm_module.c |    4 ++++
>   1 file changed, 4 insertions(+)
> 
> --- linux-next-20210901.orig/drivers/gpu/drm/ttm/ttm_module.c
> +++ linux-next-20210901/drivers/gpu/drm/ttm/ttm_module.c
> @@ -53,6 +53,9 @@ pgprot_t ttm_prot_from_caching(enum ttm_
>   	if (caching == ttm_cached)
>   		return tmp;
>   
> +#ifdef CONFIG_UML
> +	tmp = pgprot_noncached(tmp);
> +#else
>   #if defined(__i386__) || defined(__x86_64__)
>   	if (caching == ttm_write_combined)
>   		tmp = pgprot_writecombine(tmp);
> @@ -69,6 +72,7 @@ pgprot_t ttm_prot_from_caching(enum ttm_
>   #if defined(__sparc__)
>   	tmp = pgprot_noncached(tmp);
>   #endif
> +#endif
>   	return tmp;
>   }
>   

Patch looks OK.

I have a question though - why all of DRM is not !UML in config. Not 
like we can use them.

> 
> _______________________________________________
> linux-um mailing list
> linux-um@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-um
> 

-- 
Anton R. Ivanov
Cambridgegreys Limited. Registered in England. Company Number 10273661
https://www.cambridgegreys.com/

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