Cannot patch linux kernel on CentOS 5.3 (Can't find file to patch at input line)

Ouch!  Patching kernels manually is not to be done lightly unless you are very familiar with what you are doing.

Why do you want to patch your kernel?  Is there something specific a CentOS update doesn't cover?

Why will not You get the linux-2.6.29 sources tarball - why patch?
Anyway, centos kernel(RH in fact) is heavily patched already, so applying patch-2.6.19 and next will surely fail.

The system I am working on is a test system and I am for learning purposes trying to wrap my head around the kernel.

So this is merely an excercise, but from what I can see a general rule of thumb (at least for CentOS) is that there is no need to patch the kernel.

My next question would be:

1. Assuming that you need to update your kernel, what is the best method, use the source tarball files or apply a patch?
1. When should you recompile the kernel, what scenarios would prompt someone to have to recompile the kernel?
2. Along those same lines, with respect to patching, when is it a good idea to patch your kernel?  Our mainsteam distributions (i.e. CentOS, RedHat, SuSE, etc) well maintained and therefore there is no need to tinker with applying kernel patches?

You might need to update the kernel. But RedHAT kernel is highly modified form the standard. UIt is why it takes a while to be available a bit later than  the kernel sources published.

When you need to build your kernels the best practice for RedHAT is either compile the available version in that RedHAT makes available both executable and sources available. so if you need to add something you just go add and recompile.

But it you need a kernel newere than RedHAT prresents you need to go grab the kernel sources. Patches are only for people already have the previous kernel and don't have so much badwith to download again. In the end  an 2.6.20 kernel and kernel 2-6-19 and applied 2-6-10 patches ate the same thing. So patches are not add some functionality they re what makes a kernel the next release. When it comes to RedHAT you really need to know waht you're doing since they are heavily patching the kernel instead og using a stock kernel. So you need to know what the system needs this is why I'd suggested the make oldconfig to be at least compiled with same options.

Wen it comes to when to compile a kernel is some time when you need an option but it is not available as a module. For instance if you need a kernel with a higher frequency to use in hi res time processing you need to compile kernel because the only wat to modify the interrupt processing is through compiling. But when you add a new hardware you'll only need a module for the drive.

As I told earlier to patch the kernel generally means an older version into a newer version. so you need to patch the kernel when you have oledr version of sources and to add the newer functionality. There are some other cases where patches are to modify some porperties of the jkernel but they are special pathced not kernel version patches. At least none of the patches you want ot deal with in your question was of this nature.

Distro maintainers apply the patches and makes modifications so that they prepare newer versions over time so generally yeah you don't need to build your own kernel for most of the time.