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Sat, 03 Jun 2023 23:50:50 -0400 X-MC-Unique: A2_BvKP3MLuD089rbGtYyw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id BBA8D800888; Sun, 4 Jun 2023 03:50:49 +0000 (UTC) Received: from localhost (ovpn-12-83.pek2.redhat.com [10.72.12.83]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 595831410F25; Sun, 4 Jun 2023 03:50:47 +0000 (UTC) Date: Sun, 4 Jun 2023 11:50:44 +0800 From: Baoquan He To: Chen Jiahao Cc: linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, kexec@lists.infradead.org, linux-doc@vger.kernel.org, paul.walmsley@sifive.com, palmer@dabbelt.com, conor.dooley@microchip.com, guoren@kernel.org, heiko@sntech.de, bjorn@rivosinc.com, alex@ghiti.fr, akpm@linux-foundation.org, atishp@rivosinc.com, thunder.leizhen@huawei.com, horms@kernel.org Subject: Re: [PATCH -next v5 1/2] riscv: kdump: Implement crashkernel=X,[high,low] Message-ID: References: <20230511085139.1039088-1-chenjiahao16@huawei.com> <20230511085139.1039088-2-chenjiahao16@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20230511085139.1039088-2-chenjiahao16@huawei.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230603_205057_886107_46A00659 X-CRM114-Status: GOOD ( 19.45 ) X-BeenThere: linux-riscv@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-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org Hi Jiahao, On 05/11/23 at 04:51pm, Chen Jiahao wrote: ...... > @@ -1300,14 +1325,34 @@ static void __init reserve_crashkernel(void) > return; > } > > - ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(), > + ret = parse_crashkernel(cmdline, memblock_phys_mem_size(), > &crash_size, &crash_base); > - if (ret || !crash_size) > + if (ret == -ENOENT) { > + /* Fallback to crashkernel=X,[high,low] */ > + ret = parse_crashkernel_high(cmdline, 0, &crash_size, &crash_base); > + if (ret || !crash_size) > + return; > + > + /* > + * crashkernel=Y,low is valid only when crashkernel=X,high > + * is passed. > + */ > + ret = parse_crashkernel_low(cmdline, 0, &crash_low_size, &crash_base); > + if (ret == -ENOENT) > + crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE; > + else if (ret) > + return; > + > + search_end = memblock_end_of_DRAM(); > + } else if (ret || !crash_size) { > + /* Invalid argument value specified */ > return; > + } The parsing part looks great, while you didn't mark if it's specified high reservation, please see later comment why it's needed. > > crash_size = PAGE_ALIGN(crash_size); > > if (crash_base) { > + fixed_base = true; > search_start = crash_base; > search_end = crash_base + crash_size; > } > @@ -1320,17 +1365,31 @@ static void __init reserve_crashkernel(void) > * swiotlb can work on the crash kernel. > */ > crash_base = memblock_phys_alloc_range(crash_size, PMD_SIZE, > - search_start, > - min(search_end, (unsigned long) SZ_4G)); > + search_start, search_end); If it's a specified high reservation, you have search_start = memblock_start_of_DRAM(); search_end = memblock_end_of_DRAM(); Then it attempts to search top down first time here. > if (crash_base == 0) { > - /* Try again without restricting region to 32bit addressible memory */ > + if (fixed_base) { > + pr_warn("crashkernel: allocating failed with given size@offset\n"); > + return; > + } > + search_end = memblock_end_of_DRAM(); > + > + /* Try again above the region of 32bit addressible memory */ > crash_base = memblock_phys_alloc_range(crash_size, PMD_SIZE, > - search_start, search_end); > + search_start, search_end); If crashkernel=,high case, the first attempt failed, here it assigns search_end with memblock_end_of_DRAM(). It's the exactly the same attempt, why is that needed? Why don't you use a local variable 'high' to mark the crashkernel=,hig, then judge when deciding how to adjsut the reservation range. Do I misunderstand the code? Thanks Baoquan > if (crash_base == 0) { > pr_warn("crashkernel: couldn't allocate %lldKB\n", > crash_size >> 10); > return; > } > + > + if (!crash_low_size) > + crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE; > + } > + > + if ((crash_base > dma32_phys_limit - crash_low_size) && > + crash_low_size && reserve_crashkernel_low(crash_low_size)) { > + memblock_phys_free(crash_base, crash_size); > + return; > } > > pr_info("crashkernel: reserved 0x%016llx - 0x%016llx (%lld MB)\n", > -- > 2.31.1 > _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv