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Thu, 13 Aug 2026 08:05:50 -0700 (PDT) X-Received: by 2002:a05:6123:148:b0:5c1:25d4:e29c with SMTP id 71dfb90a1353d-5c579708bfbmr753776e0c.0.1786633549428; Thu, 13 Aug 2026 08:05:49 -0700 (PDT) Received: from x1.local ([174.91.117.74]) by smtp.gmail.com with ESMTPSA id 71dfb90a1353d-5c57ba66bfbsm919682e0c.2.2026.08.13.08.05.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 13 Aug 2026 08:05:48 -0700 (PDT) Date: Thu, 13 Aug 2026 11:05:45 -0400 From: Peter Xu To: Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Cc: Richard Henderson , qemu-devel@nongnu.org, Paolo Bonzini , Fabiano Rosas Subject: Re: [PULL 00/10] Next patches Message-ID: References: <20260812151444.2611689-1-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Received-SPF: pass client-ip=170.10.133.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.759, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Thu, Aug 13, 2026 at 04:51:39PM +0200, Philippe Mathieu-Daudé wrote: > On 13/8/26 16:14, Richard Henderson wrote: > > On 8/13/26 06:41, Peter Xu wrote: > > > Now when I think about it from the root, I tend to like what Xen defines > > > with ram_addr_t: > > > > > > /* address in the RAM (different from a physical address) */ > > > #if defined(CONFIG_XEN_BACKEND) > > > typedef uint64_t ram_addr_t; > > > #  define RAM_ADDR_MAX UINT64_MAX > > > #  define RAM_ADDR_FMT "%" PRIx64 > > > #else > > > typedef uintptr_t ram_addr_t; > > > #  define RAM_ADDR_MAX UINTPTR_MAX > > > #  define RAM_ADDR_FMT "%" PRIxPTR > > > #endif > > > > > > I don't know how we supported 32bit host emulating anything larger, but > > > logically it's doable, then IIUC uintptr_t won't be enough allocating > > > anything >4G? > > > > ram_addr_t != hwaddr or vaddr -- it's just an internal token. > > > > So a 32-bit machine could put 1G of ram (identified by ram_addr_t) at 8G > > (hwaddr) just fine.  But obviously it couldn't put 8G of ram anywhere.  > > :-) Yep, I should have described it as allocating >4G in total, rather in one shot. So it's about the address space we can allocate that is limited.. > > > > That said, Xen was weird in that it used to be possible to have an i386 > > qemu command-line talking to a x86_64 dom0 kernel controlling x86_64 > > guests. > > > > So, yeah, now we should drop this ram_addr_t distinction and always use > > uint64_t. > > 🩷🩷🩷 lovely 🩷🩷🩷 I can throw a patch, just to double check one last thing: we don't support any form of 32bit hosts anymore, am I right? -- Peter Xu