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LWN.net Weekly Edition for May 16, 2013
A look at the PyPy 2.0 release
PostgreSQL 9.3 beta: Federated databases and more
LWN.net Weekly Edition for May 9, 2013
(Nearly) full tickless operation in 3.10
Displaying QR codes for kernel crashes
Posted Jun 28, 2012 21:43 UTC (Thu) by mjg59 (subscriber, #23239)
Posted Jul 2, 2012 15:03 UTC (Mon) by bokr (subscriber, #58369)
kdump means sacrificing ~128MB of RAM at all times in order to have
somewhere to put the kdump kernel, and reliability on consumer hardware
is less than stellar. It's a hard problem.
How about keeping a static piece of code in the kernel that can
be executed in real mode to use BIOS to reset display to 25x80
(or whatever it was) and just loop circularly over pages of dump info,
outputting it in the most primitive way, with just hit-any-key as page
advance? IWT this shouldn't take up more than a few KB, never mind MB.
Last gasp would be to transfer to this code.
Maybe you could use box characters to generate QR codes, 3 per screen,
at 25x25 or 21x21, but that would be more code.
Posted Jul 2, 2012 15:10 UTC (Mon) by mjg59 (subscriber, #23239)
Posted Jul 2, 2012 15:20 UTC (Mon) by apoelstra (subscriber, #75205)
Posted Jul 2, 2012 15:27 UTC (Mon) by mjg59 (subscriber, #23239)
Posted Jul 2, 2012 21:03 UTC (Mon) by rvfh (subscriber, #31018)
Posted Jul 2, 2012 21:19 UTC (Mon) by mjg59 (subscriber, #23239)
Posted Jul 2, 2012 21:48 UTC (Mon) by apoelstra (subscriber, #75205)
Before then, the BIOS will give you keyboard access, tell you what drives are installed and what size they are, let you write to the screen, all sorts of wonderful stuff. For example, you can write "Hello world!" in assembler for an x86 PC, using only a couple dozen opcodes, which is very exciting when you're first learning about such a low level.
If UEFI really means the loss of all that, it makes me kinda sad.
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