linux-kernel - Re: [PATCH v1 2/2] firmware: dmi_scan: Pass dmi_entry

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Date:   Fri, 6 Sep 2019 22:00:40 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Dave Young <dyoung@...hat.com>
Cc:     Jean Delvare <jdelvare@...e.de>, kexec@...ts.infradead.org,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Eric Biederman <ebiederm@...ssion.com>,
        linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
        matt@...eblueprint.co.uk, ard.biesheuvel@...aro.org
Subject: Re: [PATCH v1 2/2] firmware: dmi_scan: Pass dmi_entry_point to
 kexec'ed kernel

On Sat, Dec 17, 2016 at 06:57:21PM +0800, Dave Young wrote:
> On 12/16/16 at 02:33pm, Jean Delvare wrote:
> > On Fri, 16 Dec 2016 14:18:58 +0200, Andy Shevchenko wrote:
> > > On Fri, 2016-12-16 at 10:32 +0800, Dave Young wrote:
> > > > On 12/15/16 at 12:28pm, Jean Delvare wrote:
> > > > > 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.
> > > 
> > > Thanks for this good news!
> > > 
> > > Unfortunately Intel Galileo is 32-bit platform.
> > 
> > If it was done for X86_64 then maybe it can be generalized to X86?
> 
> For X86_64, we have a new way for efi runtime memmory mapping, in i386
> code it still use old ioremap way. It is impossible to use same way as
> the X86_64 since the virtual address space is limited.
> 
> But maybe for 32bit, kexec kernel can run in physical mode, but I'm not
> sure, I would suggest Andy to do a test first with efi=noruntime for
> kexec 2nd kernel.

Sorry for a delay.
Eventually I found time to check this.

Unfortunately the efi=noruntime didn't help:

# uname -a
Linux buildroot 5.3.0-rc7+ #17 Thu Sep 5 16:08:22 EEST 2019 i586 GNU/Linux
# dmidecode
# dmidecode 4.2
Scanning /dev/mem for entry point.
# No SMBIOS nor DMI entry point found, sorry.
#
# cat /proc/cmdline
... ignore_loglevel efi=noruntime earlycon=efifb acpi_rsdp=0xf01e014

So, I am all ears to anything else to try.

-- 
With Best Regards,
Andy Shevchenko