Jonathan Lalou's Blog

Archive for the ‘en-US’ Category

Abstract

On migrating an application deployed through Java WebStart from JRE 6 to JRE 7 (1.7.0_71 ; the problem is present since 1.7.0_4X), system properties are ignored.
As a reminder, system properties are declared in JNLP file as:

[xml]<property name="foo" value="boo"/>[/xml]

They are equivalent to execute JRE with -D arguments, such as -Dfoo=boo for the XML block above.

Launching the JNLP file with javaws file.jnlp -Dfoo=boo or even javaws file.jnlp -J-Dfoo=boo does not fix the issue.

Quick fix

Rename all system properties, so that they are prefixed with jnlp..
Eg, replace:
[xml]<property name="foo" value="boo"/>[/xml]
with:
[xml]<property name="jnlp.foo" value="boo"/>[/xml]
Do not forget to update any part of the code calling these properties!

For a sadistic reason I still ignore, properties that are not prefixed with jnlp. are no more considered by Java WebStart included in JRE 7.

sudo update-initramfs -u -k 6.5.0

### 1.4 Kernel Initialization

dmesg | less

**Purpose**:
- Load storage drivers (LVM, RAID, encrypted disks)
- Assemble root device
- Pivot to real root

e # edit
… linux … ro single
F10 # boot

> **Use Case**: Recover root password or repair filesystem.

### 1.3 Initramfs: The Temporary Root

A compressed cpio archive loaded into RAM:

lsinitramfs /boot/initramfs-6.5.0.img | head

menuentry ‘Ubuntu’ –class ubuntu {
set root=’hd0,gpt2′
linux /vmlinuz-6.5.0 root=UUID=abc123 ro quiet splash
initrd /initramfs-6.5.0.img
}

### *Key Kernel Parameters
| Parameter | Purpose |
|--------|--------|
| `ro` | Mount root read-only initially |
| `quiet` | Suppress boot messages |
| `splash` | Show graphical boot |
 [Truncated due to length] | `systemd.unit=rescue.target` | Boot into single-user mode |
| `init=/bin/bash` | Bypass init (emergency shell) |

Stephan Linzner and Richard Hyndman, Google Android Developer Advocates, unravel enigmatic Android behaviors through interactive puzzles. Stephan, an automation aficionado and runner, teams with Richard, a 12-year mobile veteran from startups to operators, to probe component lifecycles, UI quirks, and KitKat novelties. Their session, blending polls and demos, spotlights content providers’ primacy, ViewStub pitfalls, and screen recording tools, arming developers with debugging savvy.

Android’s intricacies, they reveal, demand vigilance: from process spawning to WebView debugging. Live polls engage the audience, transforming head-scratchers into teachable moments.

Component Creation Order and Lifecycle

Stephan kicks off with a poll: which component initializes first post-process spawn? Hands favor activities, but content providers lead—crucial for data bootstrapping.

Richard demos service lifecycles, warning against onCreate leaks; broadcasts’ unregistered crashes underscore registration discipline.

UI Rendering Quirks and Optimizations

ViewStub inflation puzzles Stephan: pre-inflate for speed, but beware null children post-inflation. Richard explores ListView recycling, ensuring adapters populate recycled views correctly to avoid visual glitches.

These gotchas, they stress, demand profiler scrutiny for fluid UIs.

KitKat Innovations and Debugging Aids

KitKat’s screen recording, Richard unveils, captures high-res videos sans root—ideal for demos or Play Store assets. Stephan spotlights WebView debugging: Chrome DevTools inspect remote views, editing CSS live.

Monkey tool’s seeded crashes aid reproducible testing, simulating user chaos.

Interactive Polls and Community Insights

Polls gauge familiarity with overscan modes and transition animations, fostering engagement. The duo fields queries on SurfaceView security and WebView copies, clarifying limitations.

This collaborative format, they conclude, equips developers to conquer Android’s riddles.

Links:

• Stephan Linzner on LinkedIn
• Richard Hyndman on LinkedIn
• Google company website

ls /sys/firmware/efi # exists → UEFI

> **Security Note**: UEFI Secure Boot prevents unsigned kernels from loading—a critical defense in enterprise environments.

### 1.2 Bootloader: GRUB2

dmesg | grep -i “EFI v”