On 12/15/16 at 12:28pm, Jean Delvare wrote:
> Hi Andy,
>
> On Fri, 2 Dec 2016 21:54:16 +0200, Andy Shevchenko wrote:
> > Until now kexec'ed kernel has no clue where to look for DMI entry point.
> >
> > Pass it via kernel command line parameter in the same way as it's done for ACPI
> > RSDP.
>
> I am no kexec expert but this confuses me. Shouldn't the second kernel
> have access to the EFI systab as the first kernel does? It includes
> many more pointers than just ACPI and DMI tables, and it would seem
> inconvenient to have to pass all these addresses individually
> explicitly.
Yes, in modern linux kernel, kexec has the support for EFI, I think it
should work naturally at least in x86_64.
Is there any test log with latest mainline kernel about this?
>
> Adding Eric to Cc for his opinion.
>
> >
> > Signed-off-by: Andy Shevchenko <andriy.shevchenko at linux.intel.com>
> > ---
> > Documentation/admin-guide/kernel-parameters.txt | 5 +++++
> > drivers/firmware/dmi_scan.c | 14 ++++++++++++++
> > 2 files changed, 19 insertions(+)
> >
> > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> > index be2d6d0..94f219f 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -843,6 +843,11 @@
> > The filter can be disabled or changed to another
> > driver later using sysfs.
> >
> > + dmi_entry_point= [DMI,EFI,KEXEC]
> > + Pass the DMI entry point to the kernel, mostly used
> > + on machines running EFI runtime service to boot the
> > + second kernel for kdump.
> > +
> > drm_kms_helper.edid_firmware=[<connector>:]<file>[,[<connector>:]<file>]
> > Broken monitors, graphic adapters, KVMs and EDIDless
> > panels may send no or incorrect EDID data sets.
> > diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
> > index b88def6..215843f 100644
> > --- a/drivers/firmware/dmi_scan.c
> > +++ b/drivers/firmware/dmi_scan.c
> > @@ -595,8 +595,22 @@ static int __init dmi_smbios3_present(const u8 *buf)
> > return 1;
> > }
> >
> > +#ifdef CONFIG_KEXEC
> > +static unsigned long dmi_entry_point;
> > +static int __init setup_dmi_entry_point(char *arg)
> > +{
> > + return kstrtoul(arg, 16, &dmi_entry_point);
> > +}
> > +early_param("dmi_entry_point", setup_dmi_entry_point);
> > +#endif
> > +
> > static resource_size_t __init dmi_get_entry_point(void)
> > {
> > +#ifdef CONFIG_KEXEC
> > + if (dmi_entry_point)
> > + return dmi_entry_point;
> > +#endif
> > +
> > if (efi_enabled(EFI_CONFIG_TABLES)) {
> > /*
> > * According to the DMTF SMBIOS reference spec v3.0.0, it is
>
>
> --
> Jean Delvare
> SUSE L3 Support
>
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