Hi Geert, > > That would not work with kernel freezes unfortunately. Debugging those with > > nondeterministicly invisible kernel prints would be painful, I believe. > > Unfortunately AFAIK the PS3 doesn't have any other "synchronous" output we > can use for debugging (like flashing the power LED).
Well, one can use lv1_panic to bisect the PowerPC boot process. It either freezes, in which case the call to lv1_panic isn't reached, or it reboots. This method yields 1 bit of information for every reflash and reboot, with a procedure taking about 5 minutes per turn, so 12 bits/hour sustained. ;) The prime advantage is that lv1_panic works everywhere, including the earliest boot stages. I've since learned about the PS3GELIC_UDBG option to broadcast UDP via the Ethernet port, but I don't know how well it works or its limitations. One useful option for debugging is to setup a very early graphical console, more or less from head.S, before any kernel functions are invoked. I have a simple proof of concept implemented for the PS2 here: https://github.com/frno7/linux/blob/ps2-v4.17-n3/arch/mips/boot/compressed/dbg.c This could be done for the PS3 as well. The OtherOS demo http://mc.pp.se/ps3/oodemo.xhtml by Marcus Comstedt in 2007 contains the essentials with MMU and hypervisor initialisation for graphics. I discovered that a small patch is required to make his demo work with modern GCC: --- a/source/script.lds +++ b/source/script.lds @@ -50,6 +50,7 @@ SECTIONS .opd : { *(.opd) } + . = ALIGN(256); .got : { __toc_start = .; *(.got) Fredrik
