From: Baoquan He <bhe@redhat.com>
To: Eric DeVolder <eric.devolder@oracle.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
kexec@lists.infradead.org, ebiederm@xmission.com,
dyoung@redhat.com, vgoyal@redhat.com, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
hpa@zytor.com, nramas@linux.microsoft.com,
thomas.lendacky@amd.com, robh@kernel.org, efault@gmx.de,
rppt@kernel.org, david@redhat.com, sourabhjain@linux.ibm.com,
konrad.wilk@oracle.com, boris.ostrovsky@oracle.com
Subject: Re: [PATCH v16 7/7] x86/crash: add x86 crash hotplug support
Date: Tue, 10 Jan 2023 07:47:43 +0800 [thread overview]
Message-ID: <Y7ynnzmfy+Kxj8hQ@fedora> (raw)
In-Reply-To: <bc4ade74-dcbc-88f6-2d88-2bd4c2be38ba@oracle.com>
On 01/09/23 at 01:43pm, Eric DeVolder wrote:
>
>
> On 1/9/23 01:36, Baoquan He wrote:
> > On 01/05/23 at 10:17am, Eric DeVolder wrote:
> > ......
> > > @@ -394,10 +409,37 @@ int crash_load_segments(struct kimage *image)
> > > if (ret)
> > > return ret;
> > > - image->elf_headers = kbuf.buffer;
> > > - image->elf_headers_sz = kbuf.bufsz;
> > > + image->elf_headers = kbuf.buffer;
> > > + image->elf_headers_sz = kbuf.bufsz;
> > > + kbuf.memsz = kbuf.bufsz;
> > > +
> > > + if (IS_ENABLED(CONFIG_CRASH_HOTPLUG)) {
> > > + /*
> > > + * Ensure the elfcorehdr segment large enough for hotplug changes.
> > > + * Start with VMCOREINFO and kernel_map.
> > > + */
> > > + unsigned long pnum = 2;
> > > +
> > > + if (IS_ENABLED(CONFIG_HOTPLUG_CPU))
> > > + pnum += CONFIG_NR_CPUS_DEFAULT;
> > > +
> > > + if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))
> > > + pnum += CRASH_MAX_MEMORY_RANGES;
> >
> > Logic of pnum calculating is a little confusing to me. If I only enable
> > one of CONFIG_HOTPLUG_CPU and CONFIG_MEMORY_HOTPLUG, is it OK? Say I
> > only enable CONFIG_HOTPLUG_CPU and CONFIG_SMP, on x86_64,
> > CONFIG_NR_CPUS_DEFAULT will be 64. pnum will be 64, is it OK. Am I miss
> > anything?
>
> Ah, your understanding is correct, and the issue you point out I need to fix.
> Specifically is only one of HOTPLUG_CPU or MEMORY_HOTPLUG is set, then I need
> to allow a default for the other. Using the example you have above, there would
> not be room for a single memory region, so I need to allow for a default number
> of memory regions.
Hmm, for the above example, should we get real number of memory
regions? I am worried if the default number of memory regions
need be big enough. Because on system w/o memory hotplug, it could have
very many memory regions. The cpu number is similar.
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prev parent reply other threads:[~2023-01-09 23:48 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-05 15:17 [PATCH v16 0/7] crash: Kernel handling of CPU and memory hot un/plug Eric DeVolder
2023-01-05 15:17 ` [PATCH v16 1/7] crash: move crash_prepare_elf64_headers() Eric DeVolder
2023-01-05 15:17 ` [PATCH v16 2/7] crash: prototype change for crash_prepare_elf64_headers() Eric DeVolder
2023-01-05 15:17 ` [PATCH v16 3/7] crash: add generic infrastructure for crash hotplug support Eric DeVolder
2023-01-05 15:17 ` [PATCH v16 4/7] kexec: exclude elfcorehdr from the segment digest Eric DeVolder
2023-01-05 15:17 ` [PATCH v16 5/7] kexec: exclude hot remove cpu from elfcorehdr notes Eric DeVolder
2023-01-05 15:17 ` [PATCH v16 6/7] crash: memory and cpu hotplug sysfs attributes Eric DeVolder
2023-01-05 15:17 ` [PATCH v16 7/7] x86/crash: add x86 crash hotplug support Eric DeVolder
2023-01-09 7:36 ` Baoquan He
2023-01-09 19:43 ` Eric DeVolder
2023-01-09 23:47 ` Baoquan He [this message]
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