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Comment "page not present" statement is incorrect (Score 1) 594

In the section on performance costs, the article states that a multi-byte string copy risks crossing a VM page boundary - potentially causing a "page not present" fault - if the NUL character was the last byte of the page.

This is simply incorrect.

No memory transfer within an aligned multi-byte string copy could ever straddle a page boundary, even if the NUL character was the last byte of the page. And performance considerations should preclude a non-aligned copy, even assuming the hardware could handle non-aligned memory accesses.

Comment Non-alphanumeric characters (Score 0) 276

I used to include non-alphanumeric characters in my passwords until the following incident occurred.

I created a new account at some website. My randomly generated password consisted of alphanumeric and non-alphanumeric characters.

Some time later I returned to login to the website. It rejected my password. I tried several times but with the same result.

Then I looked at my password. One of the characters was a '#'. No, surely it can't be what I'm thinking. So I entered the password up to but not including the '#' character. Yes, password accepted; the stupid website had interpreted the '#' as the start of comment.

Comment Linux on iPAQ (Score 4, Informative) 179

I have installed Linux on an HP iPAQ hx4700 PDA (624MHz XScale PXA270, 64Mb RAM, 128Mb flash, 480x640 screen). As others have pointed out the main problems are finding (1) a boot loader and (2) drivers for your device. In the case of the hx4700 these problems were already solved for Familiar Linux (familiar.handhelds.org); SDG Systems produced a boot loader and others produced the kernel patches and drivers. A more generic boot loader is HaRET (Handheld Reverse Engineering Tool), a Linux bootloader which works from the Windows CE environment. I haven't used it myself because I wiped WinCE off my iPAQ years ago. Drivers and platforms for ARM devices are being developed for the Linux kernel all the time; check out the source code under ./arch/arm. But you may not find exactly the right combination for your device. Being a kernel hacker helps! As for a Linux distro, I first used Familiar Linux. But that is no longer actively developed. So I switched to Angstrom Linux (www.angstrom-distribution.org). But that doesn't offer the latest version of the Mozilla Fennec browser. And in both cases I found the desktop environment (e.g. GPE) to be too resource hungry. So I have now rolled my own distro from the latest software sources. In particular I am using a window manager called PAWM (Puto Amo Window Manager), which is small and perfect for a device without a keyboard, and fennec-2.0a1pre built from bleeding edge sources. Yes, they do actually work in 64Mb of RAM! It does take some effort to port, configure, debug and fix the software, but it's fun to do.

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