linux-kernel - Re: [RFC PATCH v2 3/3] resource, crash: Make kexec_file

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Message-ID: <02066f0f-dbc0-0388-4233-8e24b6f8435b@fujitsu.com>
Date:   Fri, 28 Apr 2023 07:36:22 +0000
From:   "Zhijian Li (Fujitsu)" <lizhijian@...itsu.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     "x86@...nel.org" <x86@...nel.org>,
        "nvdimm@...ts.linux.dev" <nvdimm@...ts.linux.dev>,
        "kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Yasunori Gotou (Fujitsu)" <y-goto@...itsu.com>,
        "Xiao Yang (Fujitsu)" <yangx.jy@...itsu.com>,
        "Shiyang Ruan (Fujitsu)" <ruansy.fnst@...itsu.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Eric Biederman <ebiederm@...ssion.com>,
        Takashi Iwai <tiwai@...e.de>, Baoquan He <bhe@...hat.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Sean Christopherson <seanjc@...gle.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Dan Williams <dan.j.williams@...el.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Ira Weiny <ira.weiny@...el.com>,
        Raul E Rangel <rrangel@...omium.org>,
        Colin Foster <colin.foster@...advantage.com>,
        Vishal Verma <vishal.l.verma@...el.com>
Subject: Re: [RFC PATCH v2 3/3] resource, crash: Make kexec_file_load support
 pmem

Greg,

Sorry for these *BAD* changelog, This patch is most like a *HACKing* to resource.c currently.
Please allow me to rewrite it once.

Only the region described by PT_LOADs of /proc/vmcore are dumpable/readble by dumping applications.
Previously, on x86/x86_64 only system ram resources will be injected into PT_LOADs.

So in order to make the entire pmem resource is dumpable/readable, we need to add pmem region
into the PT_LOADs of /proc/vmcore.

Here we introduce a new API walk_pmem_res() to walk the pmem region first. Further, we will also
mark pmem region with extra p_flags PF_DEV when it's adding into PT_LOADs.
Then the dumping applications are able to know if the region is pmem or not according this flag
and take special actions correspondingly.

Thanks
Zhijian


On 27/04/2023 19:39, Greg Kroah-Hartman wrote:
> On Thu, Apr 27, 2023 at 06:18:34PM +0800, Li Zhijian wrote:
>> It does:
>> 1. Add pmem region into PT_LOADs of vmcore
>> 2. Mark pmem region's p_flags as PF_DEV
> 
> I'm sorry, but I can not parse this changelog.
> 
> Please take a look at the kernel documentation for how to write a good
> changelog message so that we can properly review the change you wish to
> have accepted.
> 
> thanks,
> 
> greg k-h