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    SubjectRe: [PATCH v1 0/2] firmware: dmi_scan: Make it work in kexec'ed kernel
    On Tue, Jun 8, 2021 at 3:29 PM Dave Young <dyoung@redhat.com> wrote:
    > On 06/07/21 at 08:18pm, Andy Shevchenko wrote:
    > > On Mon, Jun 07, 2021 at 07:22:21PM +0300, Andy Shevchenko wrote:
    > > > On Sat, Jun 05, 2021 at 03:51:05PM +0800, Dave Young wrote:
    > > > > On 06/02/21 at 11:53am, Andy Shevchenko wrote:
    > > > > > On Wed, Jun 02, 2021 at 11:42:14AM +0300, Andy Shevchenko wrote:
    > > > > > > On Fri, Dec 02, 2016 at 09:54:14PM +0200, Andy Shevchenko wrote:
    > > > > > > > Until now DMI information is lost when kexec'ing. Fix this in the same way as
    > > > > > > > it has been done for ACPI RSDP.
    > > > > > > >
    > > > > > > > Series has been tested on Galileo Gen2 where DMI is used by drivers, in
    > > > > > > > particular the default I2C host speed is choosen based on DMI system
    > > > > > > > information and now gets it correct.
    > > > > > >
    > > > > > > Still nothing happens for a while and problem still exists.
    > > > > > > Can we do something about it, please?
    > > > >
    > > > > Seems I totally missed this thread. Old emails lost.
    > > >
    > > > You can always access to it via lore :-)
    > > > https://lore.kernel.org/linux-efi/20161217105721.GB6922@dhcp-128-65.nay.redhat.com/T/#u
    >
    > Thanks. Hmm, this is for 32bit efi. kexec efi boot support was only
    > added for 64bit. So if 32bit dmidecode does not work I'm not surprise.
    >
    > > >
    > > > (Okay, it's not full, but contains main parts anyway)
    > > >
    > > >
    > > > > The question Ard asked is to confirm if the firmware converted the
    > > > > SMBIOS3 addr to a virtual address after exit boot service. I do not
    > > > > remember some easy way to check it due to lost the context of the code.
    > > > > But you can try to check it via dmesg|grep SMBIOS both in normal boot
    > > > > and kexeced boot log. And then compare if those addresses are
    > > > > identical.
    > > > >
    > > > > If the SMBIOS3 addr in kexec kernel is different then it should have
    > > > > been modified by firmware. Then we need patch kernel and kexec-tools to
    > > > > support it.
    > > > >
    > > > > You can try below patch to see if it works:
    > > >
    > > > So, AFAIU I have to apply patch to kexec tools for the fist kernel + userspace
    > > > and apply kernel patch for the second kernel? Or it's all for the first one?
    > > >
    > > > > apply a kexec-tools patch to kexec-tools if you do not use kexec -s
    > > > > (kexec_file_load):
    > > >
    > > > Here is how we are using it:
    > > > https://github.com/andy-shev/buildroot/blob/intel/board/intel/common/netboot/udhcpc-script.sh#L54
    > >
    > > Okay, thanks for the patches. I have applied them to both kernels, so the first
    > > one and second one are the same and kexec tools have a patch provided in the
    > > user space of the both kernels (only first one in use though).
    > >
    > > Before applying your patch, I have reverted my hacks (as per this series).
    > >
    > > Result is:
    > >
    > > # uname -a
    > > Linux buildroot 5.13.0-rc5+ #1 SMP Mon Jun 7 19:49:40 EEST 2021 i586 GNU/Linux
    > > # dmidecode
    > > # dmidecode 3.3
    > > Scanning /dev/mem for entry point.
    > > # No SMBIOS nor DMI entry point found, sorry.
    > >
    > > I.o.w. it does NOT fix the issue. My patches do (with a hint from user space).
    >
    > As I said, since it is 32bit efi, so your test results are expected,
    > also no need to check the kernel log about SMBIOS3 address changed or
    > not.

    So, what shall I do? It's already 5 years passed without any progress
    while my patches definitely help here.
    Should I rebase and resubmit?

    --
    With Best Regards,
    Andy Shevchenko

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