(v)free the (v)mallocs!

I’m in Germany again this weekend, having been here during the week for work related reasons. I’m going to Hannover in a while and hope to have another reasonable weekend of touristy stuff combined with some writing. I need to get a bunch of articles written up soon and am looking for something fun to feature – so far it’s looking like a bit of debugging is going on in this month’s kernel column. I’m prolly gonna briefly look at Reiser 4 but much of that can wait. Spent last night (after some weissbier) going through airo.c on this Powerbook, looking for fucked up uses of ioports when the PCMCIA slot adapter goes away during suspend/resume. It’s a crash issue and I personally prefer my wifi working without random forced reboots. Also might look at the usb storage fuckup with my USB card media adapter.

I ended up knee deep in ARM VM recently, which was quite fun. I think I’m getting to like rmk’s weird sense of humour and the cleanness of the ARM code does really impress me. But still, there’s no documentation on some of this stuff. It took some figuring out to understand why modifying PHYS_OFFSET and hacking up virt_to_phys/phys_to_virt doesn’t allow me to build a kernel which can use memory at funky offsets. Turns out that another header (vmalloc.h) controls the board specific VMALLOC_START/VMALLOC_END and bases this on the offset of physical RAM (so you can have no virtual memory region if you’re not careful here). It’s all ok once you spend hours figuring it out (thanks Deepak for the IXP arch/arm/boot/Makefile entries for weird offsets – did you do that?) but the docs are painfully lacking. I will address some porting issues in a series of articles I’m proposing at the moment.

I had a McCafe last night and went for a McWalk around the industrial town I’m staying in. Then had a weird breakfast conversation with some guys who were discussing Reading (where I live in the UK) and Newbury (a town very nearby). They turn out to be hardware/software engineers and we ended up talking about all manner of crap while having our continental breakfast.

I am in my hotel room as I write this, listening to more American Idiot (Green Day). I am enjoying some of it, more for the message than the music. I need to charge my ipod (one side started to pop out the other night again – looks like a design defect to me) and head out. I could always listen to iFIRSTAID should I be really bored on the train to Hannover later on. I’ll be in Hannover until tomorrow and then I am flying back (via Frankfurt) at 14:mumble.


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