> From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@xxxxxxxxxx] > Sent: Tuesday, July 09, 2013 12:24 PM > 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> > --- > dracut.sh | 37 +++++++++++++++++++++++++++++++++---- > 1 file changed, 33 insertions(+), 4 deletions(-) > > diff --git a/dracut.sh b/dracut.sh > index 42a261e..01d96dd 100755 > --- a/dracut.sh > +++ b/dracut.sh > @@ -91,6 +91,7 @@ Creates initial ramdisk images for preloading modules > firmwares, separated by : > --kernel-only Only install kernel drivers and firmware files > --no-kernel Do not install kernel drivers and firmware > files > + --no-early-microcode Do not combine early microcode with ramdisk > --kernel-cmdline [PARAMETERS] Specify default kernel command line > parameters > --strip Strip binaries in the initramfs > --nostrip Do not strip binaries in the initramfs > @@ -376,6 +377,7 @@ while :; do > -f|--force) force=yes;; > --kernel-only) kernel_only="yes"; no_kernel="no";; > --no-kernel) kernel_only="no"; no_kernel="yes";; > + --no-early-microcode) early_microcode="no";; > --strip) do_strip_l="yes";; > --nostrip) do_strip_l="no";; > --hardlink) do_hardlink_l="yes";; > @@ -634,6 +636,7 @@ stdloglvl=$((stdloglvl + verbosity_mod_l)) > [[ $show_modules_l ]] && show_modules=$show_modules_l > [[ $nofscks_l ]] && nofscks="yes" > [[ $ro_mnt_l ]] && ro_mnt="yes" > +[[ ! $early_microcode ]] && early_microcode="yes" > # eliminate IFS hackery when messing with fw_dir > fw_dir=${fw_dir//:/ } > > @@ -659,9 +662,15 @@ readonly initdir=$(mktemp --tmpdir="$TMPDIR/" -d - > t initramfs.XXXXXX) > echo "dracut: mktemp --tmpdir=\"$TMPDIR/\" -d -t initramfs.XXXXXX > failed." >&2 > exit 1 > } > - > +if [[ $early_microcode = yes ]]; then > + readonly microcode_dir=$(mktemp --tmpdir="$TMPDIR/" -d -t > early_microcode.XXXXXX) > + [ -d "$microcode_dir" ] || { > + echo "dracut: mktemp --tmpdir=\"$TMPDIR/\" -d -t > early_microcode.XXXXXX failed." >&2 > + exit 1 > + } > +fi > # clean up after ourselves no matter how we die. > -trap 'ret=$?;[[ $outfile ]] && [[ -f $outfile.$$ ]] && rm -f > "$outfile.$$";[[ $keep ]] && echo "Not removing $initdir." >&2 || > { [[ $initdir ]] && rm -rf "$initdir";exit $ret; };' EXIT > +trap 'ret=$?;[[ $outfile ]] && [[ -f $outfile.$$ ]] && rm -f > "$outfile.$$";[[ $keep ]] && echo "Not removing $initdir." >&2 || > { [[ $initdir ]] && rm -rf "$initdir"; [[ $microcode_dir ]] && rm -Rf > "$microcode_dir"; exit $ret; };' EXIT > # clean up after ourselves no matter how we die. > trap 'exit 1;' SIGINT > > @@ -1204,11 +1213,31 @@ if [[ $do_strip = yes ]] ; then > > dinfo "*** Stripping files done ***" > fi > - > +if [[ $early_microcode = yes ]]; then > + dinfo "*** Generating early-microcode cpio image ***" > + ucode_dir=(amd-ucode intel-ucode) > + ucode_dest=(AuthenticAMD.bin GenuineIntel.bin) > + _dest_dir="$microcode_dir/d/kernel/x86/microcode" > + mkdir -p $_dest_dir > + for idx in 0 1; do > + _fw=${ucode_dir[$idx]} > + for _fwdir in $fw_dir; do > + if [[ -d $_fwdir && -d $_fwdir/$_fw ]]; then > + dinfo "*** Constructing ${ucode_dest[$idx]} ****" > + cat $_fwdir/$_fw/* > $_dest_dir/${ucode_dest[$idx]} > + fi > + done > + done > + (cd "$microcode_dir/d"; find . | cpio -o -H newc -- > quiet >../ucode.cpio) > +fi > rm -f "$outfile" > dinfo "*** Creating image file ***" > +if [[ $early_microcode = yes ]]; then > + # The microcode blob is _before_ the initramfs blob, not after > + mv $microcode_dir/ucode.cpio $outfile.$$ > +fi > if ! ( umask 077; cd "$initdir"; find . |cpio -R 0:0 -H newc -o -- > quiet| \ > - $compress > "$outfile.$$"; ); then > + $compress >> "$outfile.$$"; ); then > dfatal "dracut: creation of $outfile.$$ failed" > exit 1 > fi This patch works fine with one microcode blob in binary format. There are situations that the microcode is not delivered in one blob in binary format: First, each microcode patch is one file instead all microcode patches are in one big blob. Secondly, old delivered microcode file is in ascii format. To handle those formats, additional code needs to convert the formats into one big binary microcode blob. I'm not sure if we should consider the code and if we should put the code in dracut. Thanks. -Fenghua -- 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
