From: "Zhijian Li (Fujitsu)" <lizhijian@fujitsu.com>
To: Dan Williams <dan.j.williams@intel.com>,
Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Robert Richter <rrichter@amd.com>,
Davidlohr Bueso <dave@stgolabs.net>,
Dave Jiang <dave.jiang@intel.com>,
Alison Schofield <alison.schofield@intel.com>,
Vishal Verma <vishal.l.verma@intel.com>,
Ira Weiny <ira.weiny@intel.com>,
"linux-cxl@vger.kernel.org" <linux-cxl@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Xingtao Yao (Fujitsu)" <yaoxt.fnst@fujitsu.com>
Subject: Re: [Problem ?] cxl list show nothing after reboot Re: [PATCH v2] cxl/pci: Fix disabling memory if DVSEC CXL Range does not match a CFMWS window
Date: Tue, 9 Apr 2024 06:53:38 +0000 [thread overview]
Message-ID: <eb28ffda-d6ee-4379-9d71-b67e9f80a58c@fujitsu.com> (raw)
In-Reply-To: <66147a3e5c55f_2583ad29433@dwillia2-xfh.jf.intel.com.notmuch>
On 09/04/2024 07:14, Dan Williams wrote:
> Zhijian Li (Fujitsu) wrote:
>>
>>
>> On 06/04/2024 00:57, Jonathan Cameron wrote:
>>> On Tue, 26 Mar 2024 08:26:21 +0000
>>> "Zhijian Li (Fujitsu)" <lizhijian@fujitsu.com> wrote:
>>>
>>>> All guys,
>>>>
>>>> In order to make the CXL memdev work again, i have to modify the QEMU side
>>>> where it resets the "DVSEC CXL Control" during reboot. A draft changes is as below:
>>>>
>>>> Per 8.1.3.2 DVSEC CXL Control (Offset 0Ch), Default value of BIT(2) is 0. So is it reasonable
>>>> to have a reset dvsecs in QEMU during reboot?
>>>>
>>>> Any comments @Janathan
>>>
>>> Hi,
>>>
>>> Sorry it took me so long to get to this.
>>>
>>> What are you attempting to do? Use an OS reboot on QEMU to check that the flows
>>> meant for BIOS configuration work -
>>
>>
>> There is no doubt that *the OS rebuilds the state correctly* is the OS's responsibility.
>> Providing the consistent device state is the *Device*'s responsibility.
>>
>> So on reboot, the device should have a consistent device state with a fresh boot.
>> My changes intended to let *Device* emulated by QEMU provide a consistent
>> device state.
>
> Why? Typically the QEMU CXL enabling is for basic checkout not for
> real-world fidelity. If QEMU reboots do not result in restoring the same
> device configuration as a re-launching QEMU,
It was confirmed to be true in current QEMU, so we should fix the QEMU[1].
> why is that worth fixing?> Just document it as a quirk. Now, if it is a simple fix, great, but i> seems low priority given the enabling is really only useful for kernel
> development and relaunching QEMU is expected.
Personally, QEMU deserves a better solution than relaunching.
[1] https://lore.kernel.org/all/20240402014647.3733839-2-lizhijian@fujitsu.com/
prev parent reply other threads:[~2024-04-09 6:54 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-16 16:01 [PATCH v2] cxl/pci: Fix disabling memory if DVSEC CXL Range does not match a CFMWS window Robert Richter
2024-02-16 18:02 ` Dan Williams
2024-02-16 18:09 ` Robert Richter
2024-02-16 22:04 ` Robert Richter
2024-02-17 3:07 ` Dan Williams
2024-02-17 4:22 ` Dan Williams
2024-02-17 21:27 ` Robert Richter
2024-03-22 3:15 ` [Problem ?] cxl list show nothing after reboot " Zhijian Li (Fujitsu)
2024-03-26 8:26 ` Zhijian Li (Fujitsu)
2024-04-05 16:57 ` Jonathan Cameron
2024-04-07 3:51 ` Zhijian Li (Fujitsu)
2024-04-08 23:14 ` Dan Williams
2024-04-09 6:53 ` Zhijian Li (Fujitsu) [this message]
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