linux-kernel - Re: [PATCH] x86: Find correct 64 bit ramdisk address for microcode early update

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Message-ID: <CAE9FiQX3seRxbotg0OmLFm_WrtY-SoT9uupvZpbAqyur4Hq=aA@mail.gmail.com>
Date:	Wed, 11 Jun 2014 10:30:25 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: Find correct 64 bit ramdisk address for microcode
 early update

On Tue, Jun 10, 2014 at 11:08 PM, H. Peter Anvin <hpa@...or.com> wrote:
> On 06/10/2014 10:04 PM, Yinghai Lu wrote:
>> When using kexec with 64bit kernel, bzImage and ramdisk could be
>> loaded above 4G. We need this to get correct ramdisk adress.
>>
>> Make get_ramdisk_image() global and use it for early microcode
>> updating. Also make it to take boot_params pointer for different
>> usage.
>>
>> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
>>
>
> Have you tested this with early microcode loading on a 32-bit kernel?
>

No, I did not test that on a 32bit kernel. We did not enabled ramdisk
loading high
above 4G, right?

Do you want to me to drop changes for 32 bit path (under those MARCO)?
like:
+++ linux-2.6/arch/x86/kernel/cpu/
microcode/amd_early.c
@@ -51,12 +51,12 @@ static struct cpio_data __init find_ucod
         */
        p       = (struct boot_params *)__pa_nodebug(&boot_params);
        path    = (char *)__pa_nodebug(ucode_path);
-       start   = (void *)p->hdr.ramdisk_image;
-       size    = p->hdr.ramdisk_size;
+       start   = (void *)(unsigned long)get_ramdisk_image(p);
+       size    = get_ramdisk_size(p);

+++ linux-2.6/arch/x86/kernel/cpu/microcode/intel_early.c

        boot_params_p = (struct boot_params *)__pa_nodebug(&boot_params);
-       ramdisk_image = boot_params_p->hdr.ramdisk_
image;
-       ramdisk_size  = boot_params_p->hdr.ramdisk_size;
+       ramdisk_image = get_ramdisk_image(boot_params_p);
+       ramdisk_size  = get_ramdisk_size(boot_params_p);
        initrd_start_early = ramdisk_image;
        initrd_end_early = initrd_start_early + ramdisk_size;

BTW, Is there any 32bit bootloader that could load ramdisk above 4G?

Thanks

Yinghai
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