The other side of the moon

Sigdashes are a (de facto) way of specifying where your mail ends and your signature starts. They're pretty cool, because smart mailers and newsreaders can do funky things when they notice sigdashes.

For example, many mail clients will strip off old signatures when replying to mails. This is a Good Thing, because, hey, just one signature per mail ya?

Many mail clients, like mutt, can display signatures in a different colour or font.

So, what /are/ sigdashes?

The character sequence "dash dash space" on a line by themselves are collectively known as sigdashes. It looks something like this (without the quotes):
"-- "

Configuring your mail client to use sigdashes:

Pine:
Setup | Config
- Composer Preferences | Enable Sigdashes
- Reply Preferences | Strip From sigdashes in reply

Mutt: (sigdashes on by default)
in .muttrc, add
set sig_dashes=yes

unless it's set to "no" in /etc/Muttrc or ~/.muttrc, you do not need to do anything.

Thunderbird (via TagZilla):
In the TagZilla | Formatting screen, set Tagline Prefix to (without quotes)
"\n-- \n"

Thunderbird (no TagZilla) / Evolution / Web based mail:
Include the sigdashes line as the first line of your signature file/text.

Kmail / Outlook Express:
(No idea)


Go forth and spread the good news.

I've been using a GeForce MX 2 for well over a year. It worked quite well with RH8, FC1 and Knoppix. I needed to use the proprietary drivers provided by Nvidia to get hardware acceleration though.

Motherboard: ASUS A7N266

A couple of months ago, upgraded to FC2, and the nvidia driver wouldn't work anymore. I had to run back to Bangalore, and since no one at home really needed hardware acceleration, I switched back to the free nv driver from X (well, I was using x.org now).

This December... well, yesterday actually, I decided to try out 3ddesktop, but of course, this requires hardware acceleration. So I started. Went through a lot to get it to work, and the details are boring. However, what I learnt could help others, so I'll document that.

The problem:

When starting X with the nvidia driver, the screen blanked out and the system froze. Pushing the reset button is the only thing that worked.

Solutions and Caveats:

Get the latest NVIDIA drivers and try.

At the time of writing, the latest drivers from the nvidia site are in the 1.0-6629 package. This doesn't work with the GeForce MX 2, and many other older chips, so if you try to use it, you'll spend too much time breaking your head for nothing. Instead, go for the 1.0-6111 driver, which does work well...

On kernels below 2.6.5 that is. FC2 ships with a modified 2.6.5 kernel that has a forced 4K stack and CONFIG_REGPARM turned on. The NVIDIA drivers are (or were) compiled with 8K stacks and do not work with CONFIG_REGPARM turned on. I'd faced similar problems when I first used the nvidia driver, and recompiling my kernel with 8K stacks fixed the problem.

Searching the net, I came across dozens of articles that spoke about 4K stacks v/s 8K stacks in the 2.6 kernel, but also said that from 5xxx onwards, the nvidia driver supported 4K stacks and CONFIG_REGPARM.

I tried getting prebuilt kernels (smaller download) with 16K stacks, but it didn't help, so finally decided to downlad the entire 32MB kernel source for 2.6.10.

While compiling, I came across this thread on NV News (pretty much the best resource for nvidia issues on linux). In short, the 6111 driver wouldn't work with kernels above 2.6.5 or something like that. I needed to patch the kernel source.

The patch was tiny enough: in arch/i386/mm/init.c, add a single line:
EXPORT_SYMBOL(__VMALLOC_RESERVE);
after the __VMALLOC_RESERVE definition.

Stopped compilation, made the change and restarted compilation.

Also had to rebuild the NVIDIA driver package, again as documented in that thread:

- extract the sources with the command : ./NVIDIA-Linux-x86-1.0-6111-pkg1.run --extract-only
- in the file "./NVIDIA-Linux-x86-1.0-611-pkg1/usr/src/nv/nv.c" replace the 4 occurences of
'pci_find_class' by 'pci_get_class'
- repack the nvidia installer with the following command:

sh ./NVIDIA-Linux-x86-1.0-6111-pkg1/usr/bin/makeself.sh --target-os Linux --target-arch x86 NVIDIA-Linux-x86-1.0-6111-pkg1 NVIDIA-Linux-x86-1.0-6111-pkg2.run "NVIDIA Acclerated Graphics Driver for Linux-x86 1.0-6111" ./nvidia-installer

The new installer is called "NVIDIA-Linux-x86-1.0-6111-pkg2.run"

With these changes, the driver compiled successfully and I was able to insert it.

I had a minor problem when rebooting. usbdevfs has become usbfs, so a change has to be made in /etc/rc.sysinit. Change all occurences of "usbdevfs usbdevfs" to "usbfs none".

Once you've done this, X should start with acceleration on.

3ddesktop is slow, but it starts up. Tux racer works well.

What I think is really cool about this solution, is that I did not have to make a single post to a single mailing list or forum. All the information I needed was already on the net. It was just a matter of reading it, understanding what it said, and following those instructions. For example, there were many threads on screen blanking with the 6629 driver, and somewhere in there was mentioned that the new driver didn't support older hardware, but that the 6111 did. That was the key that brought me the solution. I knew the 6111 didn't work out of the box, because I'd already tried it, but now I could concentrate on threads about the 6111 exclusively, only looking for anything that sounded familiar.

A little over a year ago, at my previous company, I had to change my second harddisk on my PC. It was a bit of an experience, because the service engineer who came to do the job had never encountered linux before, but seemed to think that he could deal with it just like he did windows.

The engineer put in the new hard disk as a secondary master (my old one was a secondary slave to the CDD).

He then booted using a Win 95 diskette... hmm... what's this? Then started some norton disk copy utility. It's a DOS app that goes into a graphics mode... why?

Then started transferring data... hey, wait a minute, I don't have any NTFS partitions. Hit reset! Ok, cool down for a minute. I've got three ext3 partitions. So, now it's time to assess the damage.

Boot into linux - hmm, /dev/hdd1 (/home) won't mount, down to root shell. Get /home out of /etc/fstab and reboot. Ok, runlevel 3 again. Check other partitions - hdd5 (/usr) ... good, hdd6 (/usr/share) ... good... everything else is on hda... good. all my data, is in /home ... not good

So, I start trying to figure out how to recover. google... no luck. google again... one proprietary app, and a couple of howtos on recovering deleted files from ext2 partitions... no good. google again, get some docs on the structure of efs2, and find a util called e2salvage which won't build. time to start fooling around myself.

start by reading man pages. tune2fs, e2fsck, debugfs, mke2fs... so I know that mke2fs makes backups of the superblock, but where are they?

mke2fs -n /dev/hdd1... ok, that's where
dd if=/dev/hdd5 of=superblock bs=4096 count=2
hmm, so that's what a superblock looks like
dd if=/dev/hdd5 of=superblock2 bs=4096 count=2 skip=32768
hey, that's not a superblock. Ok, try various combinations, finally get this:
dd if=/dev/hdd5 of=superblock2 bs=1024 count=8 skip=131071
that's 32768*4-1
Ok, so that's where the second superblock is.

Check hdd1 - second superblock blown away as well. Look for the third... 98304*4-1=393215.. ok, that's good. should I dd it to the first? Hmm, no, e2fsck can do that for me... but, I shouldn't work on the original partition. Luckily I have 30GB of free space to play with, and /home is just 6GB.

dd if=/dev/hdd1 of=/mnt/tmp/home.img
cp home.img bak.home.img

Now I start playing with home.img.

The instructions in e2salvage said to try e2fsck before trying e2salvage, so I try that.

e2fsck home.img
no use... can't find superblock
e2fsck -b 32768 -B 4096 home.img
works... starts the fsck, and gets rid of the journal. this is gonna take too long if I do it manually, so I quit, and restart with:
e2fsck -b 32768 -B 4096 -y home.img
The other option would have been to -p(reen) it, but that wouldn't give me any messages on stdout, so I stuck with -y(es to all questions).

2 passes later it says, ok, got whatever I could.

mount -oloop,ro home.img /mnt/home
yippeee, it mounted
cd /mnt/home; ls
lost+found
ok, so everything's in lost+found, and it will take me ages to sift through all this. Filenames might give me some clues.
find . -type f | less
Ok, scroll, scroll, scroll... hmm, this looks like my home directory... yes.
cp -a \#172401 /mnt/home/philip
scroll some more, find /usr/share/doc (which I keep in /home/doc and symlink from /usr/share/doc). move it back to /usr/share/doc. find jdk1.1.8 documentation... pretend I didn't see that.

find moodle home - yay. find yabb home - yay again. Ok, find a bit more that's worth saving, and copy it over. Many files in each of these directories are corrupted, including mailboxes, and some amount of test data, but haven't found anything serious missing.

All code was in CVS anyway, so rebuilt from there where I had to.

Now decided to try e2salvage anyway, on the second copy of hdd1. It wouldn't compile. Changed some code to get it to compile, it ran, found inodes, directories and the works, then segfaulted. The program tries to read from inode 2, which doesn't exist on my partition, and then it tries to printf that inode without checking the return value.

I'd have fixed that, but the result is used in further calculations, so I just left it at that. The old hard disk was taken away, so I don't have anything to play with anymore.

It'll take me a little while to figure out all that was lost, but so far it doesn't look like anything serious.