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[66.90.148.213]) by smtp.gmail.com with ESMTPSA id x10sm424722ooa.16.2021.10.20.07.19.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 Oct 2021 07:19:47 -0700 (PDT) Received: (nullmailer pid 2299344 invoked by uid 1000); Wed, 20 Oct 2021 14:19:45 -0000 Date: Wed, 20 Oct 2021 09:19:45 -0500 From: Rob Herring To: Zhen Lei Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H . Peter Anvin" , linux-kernel@vger.kernel.org, Dave Young , Baoquan He , Vivek Goyal , Eric Biederman , kexec@lists.infradead.org, Catalin Marinas , Will Deacon , linux-arm-kernel@lists.infradead.org, Frank Rowand , devicetree@vger.kernel.org, Jonathan Corbet , linux-doc@vger.kernel.org, Randy Dunlap , Nicolas Saenz Julienne , Feng Zhou , Kefeng Wang Subject: Re: [PATCH v15 09/10] of: fdt: Add memory for devices by DT property "linux,usable-memory-range" Message-ID: References: <20211020020317.1220-1-thunder.leizhen@huawei.com> <20211020020317.1220-10-thunder.leizhen@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20211020020317.1220-10-thunder.leizhen@huawei.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211020_071950_377726_69C8A757 X-CRM114-Status: GOOD ( 32.49 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Oct 20, 2021 at 10:03:16AM +0800, Zhen Lei wrote: > From: Chen Zhou > > When reserving crashkernel in high memory, some low memory is reserved > for crash dump kernel devices and never mapped by the first kernel. > This memory range is advertised to crash dump kernel via DT property > under /chosen, > linux,usable-memory-range = > > We reused the DT property linux,usable-memory-range and made the low > memory region as the second range "BASE2 SIZE2", which keeps compatibility > with existing user-space and older kdump kernels. > > Crash dump kernel reads this property at boot time and call memblock_add() > to add the low memory region after memblock_cap_memory_range() has been > called. > > Signed-off-by: Chen Zhou > Signed-off-by: Zhen Lei > --- > drivers/of/fdt.c | 47 ++++++++++++++++++++++++++++++++++++----------- > 1 file changed, 36 insertions(+), 11 deletions(-) > > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c > index 4546572af24bbf1..cf59c847b2c28a5 100644 > --- a/drivers/of/fdt.c > +++ b/drivers/of/fdt.c > @@ -969,8 +969,16 @@ static void __init early_init_dt_check_for_elfcorehdr(unsigned long node) > elfcorehdr_addr, elfcorehdr_size); > } > > -static phys_addr_t cap_mem_addr; > -static phys_addr_t cap_mem_size; > +/* > + * The main usage of linux,usable-memory-range is for crash dump kernel. > + * Originally, the number of usable-memory regions is one. Now there may > + * be two regions, low region and high region. > + * To make compatibility with existing user-space and older kdump, the low > + * region is always the last range of linux,usable-memory-range if exist. > + */ > +#define MAX_USABLE_RANGES 2 > + > +static struct memblock_region cap_mem_regions[MAX_USABLE_RANGES]; > > /** > * early_init_dt_check_for_usable_mem_range - Decode usable memory range > @@ -979,20 +987,30 @@ static phys_addr_t cap_mem_size; > */ > static void __init early_init_dt_check_for_usable_mem_range(unsigned long node) > { > - const __be32 *prop; > - int len; > + const __be32 *prop, *endp; > + int len, nr = 0; > + struct memblock_region *rgn = &cap_mem_regions[0]; > > pr_debug("Looking for usable-memory-range property... "); > > prop = of_get_flat_dt_prop(node, "linux,usable-memory-range", &len); > - if (!prop || (len < (dt_root_addr_cells + dt_root_size_cells))) > + if (!prop) > return; > > - cap_mem_addr = dt_mem_next_cell(dt_root_addr_cells, &prop); > - cap_mem_size = dt_mem_next_cell(dt_root_size_cells, &prop); > + endp = prop + (len / sizeof(__be32)); > + while ((endp - prop) >= (dt_root_addr_cells + dt_root_size_cells)) { > + rgn->base = dt_mem_next_cell(dt_root_addr_cells, &prop); > + rgn->size = dt_mem_next_cell(dt_root_size_cells, &prop); > + > + pr_debug("cap_mem_regions[%d]: base=%pa, size=%pa\n", > + nr, &rgn->base, &rgn->size); > + > + if (++nr >= MAX_USABLE_RANGES) > + break; > + > + rgn++; > + } > > - pr_debug("cap_mem_start=%pa cap_mem_size=%pa\n", &cap_mem_addr, > - &cap_mem_size); > } > > #ifdef CONFIG_SERIAL_EARLYCON > @@ -1265,7 +1283,8 @@ bool __init early_init_dt_verify(void *params) > > void __init early_init_dt_scan_nodes(void) > { > - int rc = 0; > + int i, rc = 0; > + struct memblock_region *rgn = &cap_mem_regions[0]; > > /* Initialize {size,address}-cells info */ > of_scan_flat_dt(early_init_dt_scan_root, NULL); > @@ -1279,7 +1298,13 @@ void __init early_init_dt_scan_nodes(void) > of_scan_flat_dt(early_init_dt_scan_memory, NULL); > > /* Handle linux,usable-memory-range property */ > - memblock_cap_memory_range(cap_mem_addr, cap_mem_size); > + memblock_cap_memory_range(rgn->base, rgn->size); > + for (i = 1; i < MAX_USABLE_RANGES; i++) { > + rgn++; Just use rgn[i]. > + > + if (rgn->size) This check can be in the 'for' conditions check. > + memblock_add(rgn->base, rgn->size); > + } There's not really any point in doing all this in 2 steps. I'm assuming this needs to be handled after scanning the memory nodes, so can you refactor this moving early_init_dt_check_for_usable_mem_range out of early_init_dt_scan_chosen() and call it here. You'll have to get the offset for /chosen twice or save the offset. Rob _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel