Random Thoughts

Long ago I subscribed to the gdb.gnu.org mailing list to see if somebody could help me with my questions. It turned out not to be very useful, and when I tried to unsubscribe, it turns out it’s actually impossible. I tried everything, at some point I even sent this message to the group:

I’m sorry to contact this group for this reason, but I’ve been unable to
unsubscribe myself from the gdb.gnu.org mailing list.

I’ve sent messages to <gdb-unsubscribe@sourceware.org> and to
<gdb-unsubscribe-castano=gmail.com@sourceware.org> with the same
outcome. I got a confirmation message, that I replied to, but I
received a failure message indicating that castano@gmail.com is not a
member of the gdb.gnu.org mailing list.

> Acknowledgment: The address
>
> castano@gmail.com
>
> was not on the gdb mailing list when I received
> your request and is not a subscriber of this list.

Apparently I am, because I keep getting messages from it!

> If you unsubscribe, but continue to receive mail, you’re subscribed
> under a different address than you currently use. Please look at the
> header for:
>
> ‘Return-Path: <gdb-return-1234-user=host.dom@sourceware.org>’

The return path attribute is:

Return-Path: <gdb-bounces+castano=gmail.com@gnu.org>

> The unsubscribe address for this user would be:
> ‘gdb-unsubscribe-user=host.dom@sourceware.org’.
> Just mail to that address, substituting user=host.dom for the real
> values, reply to the confirmation request, and you should receive a message
> that you’re off the list.

That’s just what I did!

> If this still doesn’t work, I’m sorry to say that I can’t help you.
> Please FORWARD a list message together with a note about what you’re
> trying to achieve and a list of addresses that you might be subscribed
> under to my owner:
>
> gdb-owner@sourceware.org
>
> who will take care of it. My owner is a little bit slower than I am,
> so please be patient.

I also tried sending a message to <gdb-owner@sourceware.org>, but I
got an automated error message instead. It seems that gdb-owner is not
a real person:

> Hi. This is the qmail-send program at sourceware.org.
> I’m afraid I wasn’t able to deliver your message to the following addresses.
> This is a permanent error; I’ve given up. Sorry it didn’t work out.
>
> <postmaster@sourceware.org>:
>
> ezmlm-reject: fatal: Sorry, I don’t accept commands in the subject
> line. Please send a message to the -help address shown in the the
> “Mailing-List:” header for command info (#5.7.0)

Could somebody please remove me from this mailing list?

Apparently nobody could help me. Does anybody know what the hell should I do next?

I had to switch the blog to the standard template, because apparently our server received some attacks due to my custom php code. OMG I hate that white background. I’ll hopefully switch to black soon…

Intel and AMD have both released programming documentation for their hardware:

http://intellinuxgraphics.org/documentation.html

http://ati.amd.com/developer/open_gpu_documentation.html

The documentation from Intel is extremely detailed. The 965 chipset may suck performance-wise, but it has some interesting features. On one side it seems that it was designed with DX10 in mind; it supports geometry shaders, but on the other it does not support BC4-5 texture formats. Instead of these DX10-required formats it has a weird block compression format that encodes 8×4 texels in a single block.

Another interesting feature is that it support different modes of operation. Instructions can operate on AOS or SOA data structures, the former is generally used for vertex and geometry shaders, and the latter in fragment shaders. In AOS mode you can have one or two 4-element vectors processed in parallel, while in SOA mode you can have 8 or 16 scalars. What I don’t understand is why the maximum SIMD width is different in these two modes.

It isn’t clear to me either why AOS is the preferred mode for vertex processing. Are vertex shaders more divergent than fragment shaders? Is there any advantage in transposing the vertex attributes after vertex processing?

I’d like to remap my keyboard so that I’m forced to use both hands to type shortcuts like Ctrl+Letter and Alt+Letter. That means the left side of the keyboard should only work with the right modifiers, and the right side should only work with the left modifiers. Ideally I should get a beep whenever I try to use the wrong combination. Does anybody know of how to achieve that?

I’ve been fighting against the noise of my PC without any success. I’m supposed to have a super silent CPU fan, a silent power supply, and a sonata case that’s supposed to be pretty good too. It doesn’t matter, it still makes an awful lot of noise. So, I finally gave up, and bought these bose headphones with noise cancellation. Best purchase ever! They are pretty expensive, but I got them on ebay in mint condition for a 70% of the original price, and you can easily find them cheaper if you look for it. The only issue is that now I don’t hear the baby cry at night…

This evening there was a magnitude 5.6 earthquake. I’ve never felt something like that before, the noise was tremendous, the ground shacked, and the entire house trembled. Nachito looked at me as if asking: “Dad, what’s happening?”. I was paralyzed, and had no idea what was going on. I thought it was a plane crashing nearby, but when the shacking diminished I realized it was just an earthquake. I finally reacted, and grabbed Nachito. In a few seconds the noise was gone too, and everything was back to normal.

Apparently earthquakes like that happen very often around here, but I was shocked! The experience made me realize that I had no clue about what to do in that situation. I’ve heard people talk about “survival kits” and “evacuation plans”, and I thought: WTF? but the danger of an earthquake never felt so real before!

NVIDIA has launched its yearly developer survey. Filling it out is very useful for the Developer Tools, and Developer Technology groups to decide how to prioritize their tasks. So, I’d like to encourage you to do it, specially if you think that the new Texture Tools are useful, and you would like to see more open source tools like that. If you agree with me, please spend a couple of minutes, and send us your feedback!

According to the doctor I have an inflammation of the pleura. I’ve been having mild pain for the last two weeks, sometimes it becomes moderate and feels like a sharp nail crossing my lungs under my ribs. Apparently the cause is a viral infection that I got from Nachito. It’s amazing how easy it’s to get sick when you have a child.

Here’s finally portable function to detect whether the debugger is present that works on all the platforms that I care about:

bool isDebuggerPresent()
{
	bool result = false;
#if NV_OS_WIN32
	HINSTANCE kern_lib = LoadLibraryEx( "kernel32.dll", NULL, 0 );
	if( kern_lib ) {
		FARPROC lIsDebuggerPresent = GetProcAddress( kern_lib, "IsDebuggerPresent" );
		if( lIsDebuggerPresent && lIsDebuggerPresent() ) {
			result = true;
		}
		FreeLibrary( kern_lib );
	}
#elif NV_OS_DARWIN
	int mib[4];
	struct kinfo_proc info;
	size_t size;
	mib[0] = CTL_KERN;
	mib[1] = KERN_PROC;
	mib[2] = KERN_PROC_PID;
	mib[3] = getpid();
	size = sizeof(info);
	info.kp_proc.p_flag = 0;
	sysctl(mib,4,&info,&size,NULL,0);
	result = ((info.kp_proc.p_flag & P_TRACED) == P_TRACED);
#elif NV_OS_LINUX
	// if ppid != sid, some process spawned our app, probably a debugger.
	//result = getsid(getpid()) != getppid();
	char s[256];
	snprintf(s, 256, "/proc/%d/cmdline", getppid());
	FILE * fp = fopen(s, "r");
	if (fp != NULL) {
		fread(s, 256, 1, fp);
		fclose(fp);
		result = (0 == strncmp(s, "gdb", 3));
	}
#endif
	return result;
}

Checking the sid of the pid against the ppid, as I used to do, does not work in many cases. For example, it fails when running the app from a file manager such as konqueror. The better solution that I came up with is actually borrowed from Qt. It does not work with any debugger, but I just use gdb, so I don’t care. If you use a different debugger, just replace “gdb” by the corresponding command.

I use this function in the debug versions of my apps to break into the debugger when you hit an assertion, instead of throwing an exception, writing a stack trace, and exiting gracefully.

Gabi just uploaded his photos of our trip to Yosemite and Mammoth Lakes:

You should all read Naomi Klein’s powerful and inspiring speech. If you are lazy you can also watch the video.

Casual carpool also known as “slugging” is an interesting form of commuting that is used in some US cities, including San Francisco. Unfortunately it’s only limited to San Francisco and the East Bay. Benkler does an interesting analysis about it in Sharing Nicely, and compares it with other forms of social sharing practices that do not involve market mechanisms. I’m still reading through it, but so far it’s an interesting read.