linux-kernel - Re: [PATCH] x86: Unbreak early processor microcode loading

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Date:	Wed, 4 Mar 2015 10:18:47 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	Daniel J Blueman <daniel@...ascale.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Quentin Casasnovas <quentin.casasnovas@...cle.com>,
	Steffen Persvold <sp@...ascale.com>,
	linux-kernel@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH] x86: Unbreak early processor microcode loading

On Wed, Mar 04, 2015 at 04:27:12PM +0800, Daniel J Blueman wrote:
> Yes, it's built into the kernel with config:
> 
> CONFIG_FIRMWARE_IN_KERNEL=y
> CONFIG_EXTRA_FIRMWARE="amd-ucode/microcode_amd.bin
> amd-ucode/microcode_amd_fam15h.bin"
> CONFIG_EXTRA_FIRMWARE_DIR="../firmware"
> 
> That's as some customer and in-house environments we use are initramfs-less
> and some we don't have direct control over the initramfs.
> 
> I don't see why built-in microcode loading shouldn't work,

Well, it doesn't matter really. If you need to update microcode, either
with the early loader or with a built-in microcode, you'd still have to
regenerate the initrd *and* the kernel. Let me try to reproduce that
here.

Btw, you could also use the late-update method without rebooting the
machine by putting the microcode in

/lib/firmware/amd-ucode/

and doing

echo 1 > /sys/devices/system/cpu/microcode/reload

as root.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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