From: Davidlohr Bueso <dave@stgolabs.net>
To: Vishal Verma <vishal.l.verma@intel.com>
Cc: linux-cxl@vger.kernel.org, linux-acpi@vger.kernel.org,
Jonathan Cameron <Jonathan.Cameron@Huawei.com>,
Dan Williams <dan.j.williams@intel.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Robert Moore <robert.moore@intel.com>,
Bjorn Helgaas <bhelgaas@google.com>,
"Rafael J. Wysocki" <rafael@kernel.org>
Subject: Re: [PATCH v4 3/3] PCI/ACPI: negotiate CXL _OSC
Date: Fri, 1 Apr 2022 13:40:14 -0700 [thread overview]
Message-ID: <20220401204014.khgozoeu6biirknu@offworld> (raw)
In-Reply-To: <20220331202022.1823174-4-vishal.l.verma@intel.com>
On Thu, 31 Mar 2022, Vishal Verma wrote:
>The CXL specification does not define any additional constraints on
>the hotplug flow beyond PCIe native hotplug, so a kernel that supports
>native PCIe hotplug, supports CXL hotplug.
Hmm but from a Linux-pov does it make sense to allow hotplug
support if the MM cannot handle it?
@@ -531,7 +518,8 @@ static u32 calculate_cxl_support(void)
support = OSC_CXL_2_0_PORT_DEV_REG_ACCESS_SUPPORT;
if (pci_aer_available())
support |= OSC_CXL_PROTOCOL_ERR_REPORTING_SUPPORT;
- if (IS_ENABLED(CONFIG_HOTPLUG_PCI_PCIE))
+ if (IS_ENABLED(CONFIG_HOTPLUG_PCI_PCIE) &&
+ IS_ENABLED(CONFIG_MEMORY_HOTPLUG))
support |= OSC_CXL_NATIVE_HP_SUPPORT;
return support;
After all, per the CXL 2.0 Type 3 device Hot-Add flow:
""
7. CXL aware software notifies OS memory manager about the new memory and its
attributes such as latency and bandwidth. Memory manager processes a request
and adds the new memory to its allocation pool.
""
Thanks,
Davidlohr
next prev parent reply other threads:[~2022-04-01 20:40 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-31 20:20 [PATCH v4 0/3] PCI/ACPI: add support for CXL _OSC Vishal Verma
2022-03-31 20:20 ` [PATCH v4 1/3] PCI/ACPI: add a helper for retrieving _OSC Control DWORDs Vishal Verma
2022-04-05 13:39 ` Rafael J. Wysocki
2022-03-31 20:20 ` [PATCH v4 2/3] PCI/ACPI: Use CXL _OSC instead of PCIe _OSC Vishal Verma
2022-04-05 13:47 ` Rafael J. Wysocki
2022-04-05 15:59 ` Verma, Vishal L
2022-03-31 20:20 ` [PATCH v4 3/3] PCI/ACPI: negotiate CXL _OSC Vishal Verma
2022-04-01 20:40 ` Davidlohr Bueso [this message]
2022-04-01 21:34 ` Dan Williams
2022-04-04 20:30 ` Davidlohr Bueso
2022-04-05 15:57 ` Verma, Vishal L
2022-04-05 14:00 ` Rafael J. Wysocki
2022-04-05 15:55 ` Verma, Vishal L
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