[PATCH]kdump: pass noefi and acpi_rsdp= to 2nd kernel

Dave Young dyoung at redhat.com
Sun Oct 21 22:05:46 EDT 2012

On 10/18/2012 10:59 PM, Khalid Aziz wrote:

> On Thu, 2012-10-18 at 11:12 +0800, Dave Young wrote:
>> On 09/12/2012 10:35 AM, Dave Young wrote:
>>> On 09/07/2012 04:56 PM, Dave Young wrote:
>>>> I did some digging about the efi boot kdump in slackware with kernel
>>>> from latest linus tree. I'm surprise that kdump works even without these
>>>> "noefi" and "acpi_rsdp="
>>>> With fedora 17 3.4.3 kernel passing "acpi_rsdp=" is enough for kdump
>>>> kernel booting.
>>>> Actually in x86 setup code if bootloader do not pass correct efi_info in
>>>> boot_params efi_enabled will be set to 0 automaticlly.
>>>> So as for this patch 'noefi' is not needed.
>>>> I will do more testing to see why linus tree works without "acpi_rsdp="
>>> There's probably some efi changes between 3.4.3 - 3.6.0-rc4 cause this
>>> works. I have not got time to bisect it.
>> During recent test, I found I mistakenly used wrong kernel config
>> without CONFIG_EFI in 1st kernel for testing. acpi_rsdp= is still needed.
>> Just resent the v2 patch, please help to review.
> Hi Dave,
> I suspect EFI based systems with Compatibility Support Module (CSM) are
> still not going to need this, but I can see native EFI systems with no
> CSM needing this. I have reviewed your patch.

Good to know, I have no CSM machine to test. Since Simon has applied the
patch, I think I can improve this issue later If I can find a machine
with CSM.

> BTW, I am no longer at HP, so <khalid.aziz at hp.com> is no longer valid.
> <khalid at gonehiking.org> is my permanent personal email address.

Thanks for reminding.

> --
> Khalid
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