[PATCH v3 1/1] kernel/crash_core: Add crashkernel=auto for vmcore creation

[Baoquan He]

On 02/23/21 at 08:01pm, Kairui Song wrote:
> On Thu, Feb 18, 2021 at 10:03 AM Baoquan He <bhe at redhat.com> wrote:
> >
> > On 02/11/21 at 10:08am, Saeed Mirzamohammadi wrote:
...
> > > diff --git a/arch/Kconfig b/arch/Kconfig
> > > index af14a567b493..f87c88ffa2f8 100644
> > > --- a/arch/Kconfig
> > > +++ b/arch/Kconfig
> > > @@ -14,6 +14,30 @@ menu "General architecture-dependent options"
> > >  config CRASH_CORE
> > >       bool
> > >
> > > +if CRASH_CORE
> > > +
> > > +config CRASH_AUTO_STR
> > > +     string "Memory reserved for crash kernel"
> > > +     depends on CRASH_CORE
> > > +     default "1G-64G:128M,64G-1T:256M,1T-:512M"
> > > +     help
> > > +       This configures the reserved memory dependent
> > > +       on the value of System RAM. The syntax is:
> > > +       crashkernel=<range1>:<size1>[,<range2>:<size2>,...][@offset]
> > > +                   range=start-[end]
> > > +
> > > +       For example:
> > > +           crashkernel=512M-2G:64M,2G-:128M
> > > +
> > > +       This would mean:
> > > +
> > > +           1) if the RAM is smaller than 512M, then don't reserve anything
> > > +              (this is the "rescue" case)
> > > +           2) if the RAM size is between 512M and 2G (exclusive), then reserve 64M
> > > +           3) if the RAM size is larger than 2G, then reserve 128M
> > > +
> > > +endif # CRASH_CORE
> >
> > Wondering if this CRASH_CORE ifdeffery is a little redundent here
> > since CRASH_CORE dependency has been added. Except of this, I like this
> > patch. As we discussed in private threads, we can try to push it into
> > mainline and continue improving later.
> >
> 
> I believe "if CRASH_CORE" is not needed as it already "depends on
> CRASH_CORE", tested with CRASH_CORE=y or 'not set', it just works.

Thanks for testing and confirmation, Kairui.

Saeed, can you post a v4 with CRASH_CORE ifdeffery removed? Maybe this
week?

Thanks
Baoquan

> 
> > > +
> > >  config KEXEC_CORE
> > >       select CRASH_CORE
> > >       bool
> > > diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> > > index 106e4500fd53..ab0a2b4b1ffa 100644
> > > --- a/kernel/crash_core.c
> > > +++ b/kernel/crash_core.c
> > > @@ -7,6 +7,7 @@
> > >  #include <linux/crash_core.h>
> > >  #include <linux/utsname.h>
> > >  #include <linux/vmalloc.h>
> > > +#include <linux/kexec.h>
> > >
> > >  #include <asm/page.h>
> > >  #include <asm/sections.h>
> > > @@ -250,6 +251,12 @@ static int __init __parse_crashkernel(char *cmdline,
> > >       if (suffix)
> > >               return parse_crashkernel_suffix(ck_cmdline, crash_size,
> > >                               suffix);
> > > +#ifdef CONFIG_CRASH_AUTO_STR
> > > +     if (strncmp(ck_cmdline, "auto", 4) == 0) {
> > > +             ck_cmdline = CONFIG_CRASH_AUTO_STR;
> > > +             pr_info("Using crashkernel=auto, the size chosen is a best effort estimation.\n");
> > > +     }
> > > +#endif
> > >       /*
> > >        * if the commandline contains a ':', then that's the extended
> > >        * syntax -- if not, it must be the classic syntax
> > > --
> > > 2.27.0
> > >
> >
> >
> > _______________________________________________
> > kexec mailing list
> > kexec at lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/kexec
> >
> 
> 
> -- 
> Best Regards,
> Kairui Song
>