On 07/12/2013 11:02 PM, Konrad Rzeszutek Wilk wrote: > From 5f853d2ececd4cadff648e22cb9c9287a01a9783 Mon Sep 17 00:00:00 2001 > From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> > Date: Tue, 9 Jul 2013 13:57:01 -0400 > Subject: [PATCH] dracut.sh: Support early microcode loading. > > Implement it per Linux kernel Documentation/x86/early-microcode.txt > (from v3.11-rc0): > > <start> > Early load microcode > ==================== > By Fenghua Yu <fenghua.yu@xxxxxxxxx> > > Kernel can update microcode in early phase of boot time. Loading microcode early > can fix CPU issues before they are observed during kernel boot time. > > Microcode is stored in an initrd file. The microcode is read from the initrd > file and loaded to CPUs during boot time. > > The format of the combined initrd image is microcode in cpio format followed by > the initrd image (maybe compressed). Kernel parses the combined initrd image > during boot time. The microcode file in cpio name space is: > on Intel: kernel/x86/microcode/GenuineIntel.bin > on AMD : kernel/x86/microcode/AuthenticAMD.bin > > During BSP boot (before SMP starts), if the kernel finds the microcode file in > the initrd file, it parses the microcode and saves matching microcode in memory. > If matching microcode is found, it will be uploaded in BSP and later on in all > APs. > > The cached microcode patch is applied when CPUs resume from a sleep state. > > There are two legacy user space interfaces to load microcode, either through > /dev/cpu/microcode or through /sys/devices/system/cpu/microcode/reload file > in sysfs. > > In addition to these two legacy methods, the early loading method described > here is the third method with which microcode can be uploaded to a system's > CPUs. > > The following example script shows how to generate a new combined initrd file in > /boot/initrd-3.5.0.ucode.img with original microcode microcode.bin and > original initrd image /boot/initrd-3.5.0.img. > > mkdir initrd > cd initrd > mkdir -p kernel/x86/microcode > cp ../microcode.bin kernel/x86/microcode/GenuineIntel.bin (or AuthenticAMD.bin) > find . | cpio -o -H newc >../ucode.cpio > cd .. > cat ucode.cpio /boot/initrd-3.5.0.img >/boot/initrd-3.5.0.ucode.img > <end> > > That is what we do in the patch. Furthermoere there is also > an off-switch: "no-early-microcode" to disable it. > > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> > [v1: Support --host-only parameter] > --- > dracut-functions.sh | 33 +++++++++++++++++++++++++++++++++ > dracut.sh | 46 ++++++++++++++++++++++++++++++++++++++++++---- > 2 files changed, 75 insertions(+), 4 deletions(-) > Pushed to dracut git HEAD, but disabled by default, also added the --early-microcode option and bash cimpletion. Man pages still need documentation. lsinitrd only displays the microcode files at the moment of course. This is tricky to solve. Any ideas? -- To unsubscribe from this list: send the line "unsubscribe initramfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
