Re: [PATCH v4 1/3] kexec: Move vmcoreinfo out of the kernel's .bss section

From	Dave Young <dyoung@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v4 1/3] kexec: Move vmcoreinfo out of the kernel's .bss section
Date	2017-04-27 05:10 +0200
Message-ID	<tAHYB-31M-5@gated-at.bofh.it> (permalink)
References	<tyiKZ-8qv-1@gated-at.bofh.it> <tApoZ-7rG-3@gated-at.bofh.it> <tArTQ-yp-23@gated-at.bofh.it> <tAsdc-UH-15@gated-at.bofh.it>
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[snip]
> >>>  
> >>>  static int __init crash_save_vmcoreinfo_init(void)
> >>>  {
> >>> +	/* One page should be enough for VMCOREINFO_BYTES under all archs */
> >> Can we add a comment in the VMCOREINFO_BYTES header file about the one
> >> page assumption?
> >>
> >> Or just define the VMCOREINFO_BYTES as PAGE_SIZE instead of 4096
> > Yes, I considered this before, but VMCOREINFO_BYTES is also used by VMCOREINFO_NOTE_SIZE
> > definition which is exported to sysfs, also some platform has larger page size(64KB), so
> > I didn't touch this 4096 value.
> >
> > I think I should use kmalloc() to allocate both of them, then move this comment to Patch3 
> > kimage_crash_copy_vmcoreinfo().
> 
> But on the other hand, using a separate page for them seems safer compared with
> using frequently-used slab, what's your opinion?

I feel current page based way is better.

For 64k page the vmcore note size will increase it seems fine. Do you
have concern in mind?

Thanks

Thread

Re: [PATCH v4 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Dave Young <dyoung@redhat.com> - 2017-04-26 09:20 +0200
  Re: [PATCH v4 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Xunlei Pang <xpang@redhat.com> - 2017-04-26 12:00 +0200
    Re: [PATCH v4 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Xunlei Pang <xpang@redhat.com> - 2017-04-26 12:20 +0200
      Re: [PATCH v4 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Dave Young <dyoung@redhat.com> - 2017-04-27 05:10 +0200
        Re: [PATCH v4 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Xunlei Pang <xpang@redhat.com> - 2017-04-27 07:30 +0200
          Re: [PATCH v4 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Dave Young <dyoung@redhat.com> - 2017-04-27 07:50 +0200
            Re: [PATCH v4 1/3] kexec: Move vmcoreinfo out of the kernel's .bss  section Xunlei Pang <xpang@redhat.com> - 2017-04-27 08:10 +0200

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