linux-kernel - Re: [PATCH] x86/boot: Use EFI setup data if provided

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Date:   Mon, 25 Mar 2019 08:53:51 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Baoquan He <bhe@...hat.com>
Cc:     Junichi Nomura <j-nomura@...jp.nec.com>,
        "fanc.fnst@...fujitsu.com" <fanc.fnst@...fujitsu.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>
Subject: Re: [PATCH] x86/boot: Use EFI setup data if provided

On Mon, Mar 25, 2019 at 03:27:10PM +0800, Baoquan He wrote:
> Kexec kernel also need to get rsdp to get SRAT tables so that KASLR can
> avoid those hotpluggable regions in boot compression stage.
> 
> The kexec_file_load has filled in acpi_rsdp_addr of kexec kernel in
> below code. It will return direclty in get_rsdp_addr() since
> acpi_rsdp_addr is got from boot_params->acpi_rsdp_addr.
> 
> arch/x86/kernel/kexec-bzimage64.c <<setup_boot_parameters>>
> 	params->acpi_rsdp_addr = boot_params.acpi_rsdp_addr;
> 
> The other interface, kexec_load, its boot_params filling is done in user
> space kexec_tools. And we haven't made the acpi_rsdp_addr filling yet.
> And the old kexec_tools utility can also cause the new kexec kernel to
> search efi rspd pointer even thought it's fixed.

Yes, kexec is a pile of ugly and fragile hackery.

-- 
Regards/Gruss,
    Boris.

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