[XCSSA] updating a kernel without rebooting

[xcssa@xcssa.org]

On 8/17/06, xcssa-admin@xcssa.org <xcssa-admin@xcssa.org> wrote:
> The general linux releases do NOT have a very stable/consistent system
> level API (e.g. see solaris or 'windows') between OS releases, so, not
> likely.

Doesn't matter.  There's no problem here that installing a kernel and
rebooting fixes.  If your application-level binaries don't work with a
new kernel, then they don't work even if you reboot with that kernel.
And I beg to differ about the API.  The Win32 API changes (in terms of
adding) stuff all the time.  The fact is that Win32 can hide the
differences by emulating the old API in its kernel mode "libraries",
and userland apps look up the kernel level routines just like you
would in user mode with a dynamic library.  If they want a new system
call, they just add a new routine.  This is why all the Windows
exploits have to know which version of Windows you're running, because
they don't do symbol lookups like normal programs.  They have to jump
straight to memory addresses, which vary from release to release.

OTOH, in x86 Linux, the only "lookup" that is done is when a libc stub
maps to a trap to kernel mode via int 0x80.  The system call _number_
is stored in EAX IIRC.  If someone wants to change the arguments or
semantics of a system call, or add a new one, there is intense debate!
 I don't recall exactly why right now (look at the time), but it was a
good reason.  Maybe binary emulation on other OSes?

g'nite!
-- 
"If you're not part of the solution, you're part of the precipitate."
Unix "guru" for rent or hire -><- http://www.lightconsulting.com/~travis/
GPG fingerprint: 9D3F 395A DAC5 5CCC 9066  151D 0A6B 4098 0C55 1484