Date: Tue, 29 Mar 2022 09:57:40 +0000 From: =?utf-8?B?Q29ydmluIEvDtmhuZQ==?= <C.Koehne@beckhoff.com> To: Gerd Hoffmann <kraxel@redhat.com>, "devel@edk2.groups.io" <devel@edk2.groups.io> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>, Jiewen Yao <jiewen.yao@intel.com>, Jordan Justen <jordan.l.justen@intel.com>, "Rebecca Cran" <rebecca@bsdio.com>, Peter Grehan <grehan@freebsd.org>, "FreeBSD Virtualization" <freebsd-virtualization@freebsd.org> Subject: RE: [edk2-devel] [PATCH 0/1] OvmfPkg/Bhyve: QemuFwCfg support Message-ID: <ff1769bd124140d799c2fd7917004a6a@beckhoff.com> In-Reply-To: <20220329091406.jp3e4bwdmyre6pnc@sirius.home.kraxel.org> References: <20220329065437.186-1-c.koehne@beckhoff.com> <20220329091406.jp3e4bwdmyre6pnc@sirius.home.kraxel.org>
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Hi Gerd, > There is FW_CFG_NB_CPUS + FW_CFG_MAX_CPUS. ovmf uses different names, > see OvmfPkg/Include/IndustryStandard/QemuFwCfg.h > > PlatformPei for qemu uses QemuFwCfgItemSmpCpuCount aka FW_CFG_NB_CPUS, > which is the number of cpus which are online. > > I think FW_CFG_MAX_CPUS is basically unused these days. It played a > role back when seabios created the acpi tables for cpu hotplug as > described in the comment above. In qemu 2.0 & newer the acpi tables are > generated by qemu instead. The firmware just downloads them from fw_cfg > and installs them for the OS, it doesn't need to know virtual machine > configuration details any more. The FwCfgItem of this patch is used by bhyve to build the MADT. So, it's similar to the use case of FW_CFG_MAX_CPUS. At the moment, I'm using an additional bhyve specific FwCfgItem. I just want to ask, if it makes sense to use FW_CFG_MAX_CPUS to avoid two items for the same purpose or to keep it as is. Best regards Corvin Beckhoff Automation GmbH & Co. KG | Managing Director: Dipl. Phys. Hans Beckhoff Registered office: Verl, Germany | Register court: Guetersloh HRA 7075
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