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Shutemov" Cc: Dave Hansen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Jonathan Corbet , Andy Lutomirski , Peter Zijlstra , Ard Biesheuvel , Jan Kiszka , Kieran Bingham , Michael Roth , Rick Edgecombe , Brijesh Singh , Sandipan Das , Juergen Gross , Tom Lendacky , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-efi@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCHv3 2/4] x86/64/mm: Make SPARSEMEM_VMEMMAP the only memory model Message-ID: References: <20250516123306.3812286-1-kirill.shutemov@linux.intel.com> <20250516123306.3812286-3-kirill.shutemov@linux.intel.com> <30570ca0-8da4-4ebc-84d6-0a4badfb7154@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: DDB4A140019 X-Stat-Signature: 63hhsdc55pfupx3miwxpm99jg83sbowf X-Rspam-User: X-HE-Tag: 1747404502-532408 X-HE-Meta: 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 9IUAN9PJ NTU575tJjX2TpENLgw0q6cFznfR8XsUfhQwRN40GlXrQ3XpQ6qC/vkDt6CUsPclqPj3vFci51oNTXtdpbGSeR/446wgEzRt7Wc/9qd6rRyN8U+JokhomBchCJtAJzGkDXe3vpOlZUs0L87s1/W4kuTtMPtPI/86/wpc0KFZyXI3eAPBwZpNLKLCtNF5wZIsRPVje/K0E2jdJ/kIKdraTu9duA3mWXZTPSeITxeOR1M2HSUD7yL2KOzd4RCy4tbMmkD82CLKCJsVPTGlAmIea6agrim0tXiP+ZjkgG X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: * Kirill A. Shutemov wrote: > On Fri, May 16, 2025 at 06:42:03AM -0700, Dave Hansen wrote: > > On 5/16/25 05:33, Kirill A. Shutemov wrote: > > > 5-level paging only supports SPARSEMEM_VMEMMAP. CONFIG_X86_5LEVEL is > > > being phased out, making 5-level paging support mandatory. > > > > > > Make CONFIG_SPARSEMEM_VMEMMAP mandatory for x86-64 and eliminate > > > any associated conditional statements. > > I think we have ourselves a catch-22 here. > > > > SPARSEMEM_VMEMMAP was selected because the other sparsemem modes > > couldn't handle a dynamic MAX_PHYS{MEM,ADDR}_BITS introduced by 5-level > > paging. Now you're proposing making it static again, but keeping the > > SPARSEMEM_VMEMMAP dependency. > > > > If you remove the dynamic MAX_PHYS{MEM,ADDR}_BITS, you should also > > remove the dependency on SPARSEMEM_VMEMMAP. No? > > I guess. But how? > > And is there any value to support !SPARSEMEM_VMEMMAP? Not really IMHO: .config.opensuse.default: CONFIG_SPARSEMEM_VMEMMAP_ENABLE=y .config.ubuntu.localinstall: CONFIG_SPARSEMEM_VMEMMAP_ENABLE=y .config.fedora.generic: CONFIG_SPARSEMEM_VMEMMAP_ENABLE=y .config.rhel.generic: CONFIG_SPARSEMEM_VMEMMAP_ENABLE=y Thanks, Ingo