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Date:   Wed, 11 May 2022 16:40:33 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Mike Rapoport <rppt@kernel.org>
Cc:     Christoph Hellwig <hch@lst.de>, Conor.Dooley@microchip.com,
        sfr@canb.auug.org.au, linux-next@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org
Subject: Re: linux-next: Tree for May 3
Message-ID: <20220511144033.GA1478@lst.de>
References: <dd946220-eaf6-773a-06b4-307cda466c9c@microchip.com> <505d41d1-1bc8-c8bc-5ebb-8a2b7934f3de@microchip.com> <20220511062232.GA32524@lst.de> <102578f2-5c10-e9c2-c1ef-e76ba90d011e@microchip.com> <20220511064832.GA761@lst.de> <2c0e2fbe-4e45-4acc-c2a7-4f4dcf9161a3@microchip.com> <20220511123724.GA25121@lst.de> <YnvDdPz4S5IJ7l/5@kernel.org> <20220511141034.GA31732@lst.de> <YnvKPu5uQ8rqEcvV@kernel.org>
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On Wed, May 11, 2022 at 05:37:50PM +0300, Mike Rapoport wrote:
> Presuming that devices see [0x1000200000-0x103fffffff] as
> [0x200000-0x3fffffff] we may try something like
> 
> 	min = memblock_start_of_DRAM();
> 	max = min + 0xffffffff;
> 
> 	if (flags & SWIOTLB_ANY)
> 		max = MEMBLOCK_ALLOC_ACCESSIBLE;
> 
> 	tlb = memblock_alloc_try_nid(bytes, PAGE_SIZE, min, max, NUMA_NO_NODE);

While there is still no guarantee the first 32-bits worth of DRAM
are actually mapped to a usable address, this looks like a much better
default than what we have right now.