HDA Intel Alsa volume low
I've been having a problem where the volume level of my Dell Studio 17 notebook is just not loud enough when I'm running Linux. I went to windows, to see if the problem was the same there, and I found that the volume in Windows Vista was way higher. So, I booted back into Linux, and started googling.
I quickly found a few places that talked about setting the model to 3stack, and various other options. But, none of that worked for me. So, I decided to search for the problem on my own. I ended up checking out the alsamixer again, from the command line. Last time I checked, I saw that the "Speaker" volume was set to about two thirds, but I had thought that was referring to the volume of the PC Speaker, as on many sound cards, it is actually an option. As it is, that is actually the volume of the external speaker. Once you pump that puppy up to 100% the volume level is good. From there, you can simply adjust the master or PCM volumes as you choose.
Java, Xalan, JAXP, xml transformations from Java String
I racked my head against the wall over and over again for several hours, unable to determine why I was getting a prolog error, when I knew dang well my XML was well formed.
I'm using JAXP, which is detecting and using xalan as my transformation implementation. I'm not sure who's fault it is, but when I create a new StreamSource for my transformation, and I ask it to load the xml-stylesheet from the processing instruction, it simply doesn't work. I keep getting one of two errors, depending on the format of the java String.
The first error I was getting was "javax.xml.transform.TransformerException: Content is not allowed in prolog". The other error I was getting, once I put my xml declaration at the beginning of the string, was "javax.xml.transform.TransformerException: The markup in the document following the root element must be well-formed". Of course, none of these are meaningful in any way. Neither one tells me that I'm not allowed to ask xalan to resolve my xml-stylesheet automatically, while using XML from a Java String object.
MMC/SDHC Card Readers and Gentoo Linux
So, I had a need to use my SDHC card in my Dell Studio 17 (1737) notebook. So, I set out to find out why it wasn't working. I ended up finding out that I needed to load mmc_block and sdhci-pci in order to get it to work. Here's what I did.
Quick Guide to LUKS Encrypted Home Volumes
If you search for information on how to do LUKS encrypted home volumes, you're likely to get these big fluffy documents on how to do it. Well, if you're like me, you'd like to skip all that fluff, and get straight to the point. That's what I try to do here. If you like, you can completely ignore what I'm saying here, and just use the commands; it really isn't complex.
Keep in mind that this will only work for a maximum of 8 users per system. Anything more than that, and you will have to resort to either full disk encryption, or some other method of encrypting your /home files.
I would try this out on a 1G volume or something just for fooling around. Then once you've got that working, do it to your actual home directory. I use LVM with mine, but it could also be a raw partition if you prefer that. If it is a removable drive, I HIGHLY recommend using LVM, because you will be able to reference it by lvm "name". Using a partition for external drives becomes difficult, because you cannot name an encrypted volume.
arduino interfacing with the HD44780 LCD
It became time for me to interface an LCD with my Arduino. I need to generate a handy report of what my various sensors are picking up. The following is an account of my notes on twisting up my HD44780 compatible LCD on the Arduino. Please enjoy.
I'm staring at my LCD module. I can hear it saying, "hook me up!", but I'll have to read a bit first.
Linux Macbook Function Key Mode – fnmode
So, I couldn't figure out how to get my Macbook function keys to default to function keys under Linux, rather than media keys such as brightness, volume control, etc. I searched all over the net for information on this feature, and could only find stuff about pb_fnmode (which doesn't appear in the latest kernels). So, I finally resorted to grepping "fnmode" out of the sources, and found the location that sets this. Then, I noticed that the kernel module that handles Mac key mappings had a parameter that could be changed, called "fnmode". Well, that gave me a clue that it may be in /sys/ somehwere. So, I searched, and sure enough, it was there. The following command will set the function keys to be the default action, rather than media keys.
echo 2 > /sys/module/hid_apple/parameters/fnmode
The valid values are (0 = disabled, [1] = fkeyslast, 2 = fkeysfirst)
This effectively reverses the function key/media key mappings.
Kingston Rocks
If you plan on buying memory, it most certainly MUST be Kingston memory. I bought 4G of Kingston memory from CDW Canada, for my Macbook, and it was DOA. I tried it in my Macbook; Linux was freezing up, and Mac OS X was telling me I had to restart my computer.
CDW doesn't do returns, so I called up Kingston. I told them the situation, about how I put the memory in my computer, and my computer quit working, but works with my other RAM. They immediately issued me an RMA number, and told me that they would be emailing me instructions on how to send it back through fedex; the fedex charges would be billed to them. I'm like "WHAT"???? You guys are paying the shipping charges? I was totally expecting to have to pay shipping myself. So, I proceeded to ask if they were paying shipping charges because I had just purchased it, or if this was the case for the life of the product. She told me that it was included with the lifetime warranty.
Now that is what I call a lifetime warranty. So, suffice it to say, I will only buy Kingston memory. KINGSTON ROCKS!!!
vmware modules 2.6.30-rc3
If you are using VMware-Workstation-6.5.1-126130.x86_64, you will find that it does not work on kernels greater than or equal to 2.6.29. The vmware modules will not load. I found one patch for vmware to work with the Linux kernel 2.6.29 on the vmware forums, and I came up with another patch for 2.6.30-rc3 on my own. If you know who made the original patch (as I have lost the link to the forum), please let me know who that is so I can give credit where credit is due. Below are the results.
I have tried these changes on 2.6.30-rc3, and 2.6.30-rc7, and they seem to work fine. I would imagine that they would work on 2.6.30-rc3, 2.6.30-rc4, 2.6.30-rc5, 2.6.30-rc6, and 2.6.30-rc7, but I have not confirmed. They may also work on 2.6.30 versions that are less than rc3.
Recover LVM Volume Groups and Logical Volumes WITHOUT Backups
I recently had a misfortune, in that somehow my volume group meta-data got corrupted, and LVM would not enable the volume group. Essentially, I lost my LVM volume disk. This happened after I resized a volume, and had done a file system check before and after. So, I knew my data was still there.
I did an lvextend on my primary logical volume. Normally this is a routine task, but for some reason, things went very badly for me this time around. I did an "fsck -f" before and after extending the volume and the filesystem (with resize2fs). Everything checked out just fine, so I thought everything was done, and ready to reboot.
