12297: Difference between revisions

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* download the [http://dev.laptop.org/pub/firmware/q7b43/q7b43.rom q7b43.rom] old firmware,
* download the [http://dev.laptop.org/pub/firmware/q7b43/q7b43.rom q7b43.rom] old firmware,
* copy both to a USB drive,
* copy both to a USB drive,
* <font color="red">note</font>: remove the /bootpart/boot/bootfw.zip file, to prevent automatic firmware upgrade,
* <font color="red">note</font>: remove the /bootpart/boot/bootfw4.zip file, to prevent automatic firmware upgrade;
rm /bootpart/boot/bootfw4.zip
* downgrade the kernel,
* downgrade the kernel, by forcing upgrade to lower version;
rpm --upgrade --force \
kernel-3.5.7_xo4-20141118.2329.olpc.cd558cf.armv7hl.rpm
* shutdown,
* shutdown,
sudo poweroff
sudo poweroff

Revision as of 21:53, 14 January 2015

OLPC has begun enabling the second processor core in the XO-4 laptops.

Problem

The released operating systems 13.2.1 and 13.2.2 run only one core. The XO-4 underperforms compared to some other devices.

Solution

XO-4 only:

Upgrade to 14.1.0 once it is released

Workaround

Care is needed. Without the firmware upgrade, our dual-core kernel will not boot. With the firmware upgrade, the original kernel will not boot. The reason for the restriction is that changes to firmware and kernel must occur at the same time.

On unsecure laptops running 13.2.0, 13.2.1 and 13.2.2, upgrade the kernel and the firmware at the same time. The exact steps are:

sudo rpm -U kernel-3.5.7_xo4-20150108.2115.olpc.b2c8f99.armv7hl.rpm
  • shutdown,
sudo poweroff
  • upgrade the firmware,
ok flash u:\q7c02.rom
  • allow the laptop to boot.

Reverting

sudo poweroff
  • downgrade the firmware,
ok flash u:\q7b43.rom
  • allow the laptop to boot.

Using a single core kernel on 14.1.0

Certain tasks may benefit from the higher memory bandwidth of the single core kernel.

rm /bootpart/boot/bootfw4.zip
  • downgrade the kernel, by forcing upgrade to lower version;
rpm --upgrade --force \
kernel-3.5.7_xo4-20141118.2329.olpc.cd558cf.armv7hl.rpm
  • shutdown,
sudo poweroff
  • downgrade the firmware,
ok flash u:\q7b43.rom
  • allow the laptop to boot.

See Also