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Date: Tue, 25 Mar 2025 15:23:52 +0000
From: Simon Horman <horms@kernel.org>
To: Alejandro Lucero Palau <alucerop@amd.com>
Cc: alejandro.lucero-palau@amd.com, linux-cxl@vger.kernel.org,
	netdev@vger.kernel.org, dan.j.williams@intel.com,
	edward.cree@amd.com, davem@davemloft.net, kuba@kernel.org,
	pabeni@redhat.com, edumazet@google.com, dave.jiang@intel.com
Subject: Re: [PATCH v11 13/23] cxl: define a driver interface for DPA
 allocation
Message-ID: <20250325152352.GT892515@horms.kernel.org>
References: <20250310210340.3234884-1-alejandro.lucero-palau@amd.com>
 <20250310210340.3234884-14-alejandro.lucero-palau@amd.com>
 <20250320161847.GA892515@horms.kernel.org>
 <3af51327-7745-4b18-a478-f47c57683576@amd.com>
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In-Reply-To: <3af51327-7745-4b18-a478-f47c57683576@amd.com>

On Mon, Mar 24, 2025 at 04:16:05PM +0000, Alejandro Lucero Palau wrote:
> 
> On 3/20/25 16:18, Simon Horman wrote:
> > On Mon, Mar 10, 2025 at 09:03:30PM +0000, alejandro.lucero-palau@amd.com wrote:
> > > From: Alejandro Lucero <alucerop@amd.com>
> > > 
> > > Region creation involves finding available DPA (device-physical-address)
> > > capacity to map into HPA (host-physical-address) space. Define an API,
> > > cxl_request_dpa(), that tries to allocate the DPA memory the driver
> > > requires to operate. The memory requested should not be bigger than the
> > > max available HPA obtained previously with cxl_get_hpa_freespace.
> > > 
> > > Based on https://lore.kernel.org/linux-cxl/168592158743.1948938.7622563891193802610.stgit@dwillia2-xfh.jf.intel.com/
> > > 
> > > Signed-off-by: Alejandro Lucero <alucerop@amd.com>
> > Hi Alejandro,
> 
> 
> Hi Simon,
> 
> 
> > 
> > As reported by the Kernel Test Robot, in some circumstances this
> > patch fails to build.
> > 
> > I did not see this with x86_64 or arm64 allmodconfig.
> > But I did see the problem on ARM and was able to reproduce it (quickly)
> > like this using the toolchain here [*].
> > 
> > $ PATH=.../gcc-12.3.0-nolibc/arm-linux-gnueabi/bin:$PATH
> > 
> > $ ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- make allmodconfig
> > $ echo CONFIG_GCC_PLUGINS=n >> .config
> > $ ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- make oldconfig
> > 
> > $ ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- make drivers/cxl/core/hdm.o
> > ...
> >    CC [M]  drivers/cxl/core/hdm.o
> > In file included from drivers/cxl/core/hdm.c:6:
> > ./include/cxl/cxl.h:150:22: error: field 'dpa_range' has incomplete type
> >    150 |         struct range dpa_range;
> >        |                      ^~~~~~~~~
> > ./include/cxl/cxl.h:221:30: error: field 'range' has incomplete type
> >    221 |                 struct range range;
> >        |
> > 
> > [*] https://mirrors.edge.kernel.org/pub/tools/crosstool/files/bin/x86_64/14.2.0/
> > 
> > ...
> 
> 
> Thanks for the references. I'll try it and figure out what is required.

Thanks,

I realised after posting that PATH above uses gcc-12.3 while the link
above is for gcc-14.2.0. Which is inconsistent. But in practice I tried both :)

...