Messages in this thread | | | From | "Frantisek Rysanek" <> | Date | Wed, 23 Apr 2008 14:19:25 +0200 | Subject | Re: What pokes the ISA IO port of 0x211 ? |
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On 21 Apr 2008 at 19:40, H. Peter Anvin wrote: > It might be easiest to put in a hack in the kernel by hacking > outb/outw/outl and print stack trace when called when trying to poke > this port.
On 21 Apr 2008 at 22:34, Rene Herman wrote: > Ah, it's the old analog gameport: ns558_init.
Well my immediate initial idea was indeed the game port, IO port 0x201 immediately started jumping up and down in the dark recesses of my memory from teenage years, when I was trying this and that in Borland C in DOS...
So even before I wrote to LKML, I went into "make menuconfig" and made sure that any entries related to the game port were disabled:
Device Drivers --> Input device support --> Joystick interface = disabled Joysticks/Gamepads = disabled
I've been having all of that disabled in my kernel for ages, I haven't met a game port since I abandoned my 486+SB16.
So, after Rene's response and HPA's responses, I resorted to the suggested hacking on include/asm/io.h .
After some grepping through the kernel sources, I could come up with a simple call to dump_stack(). I added if (port == 0x211) dump_stack();\ into <asm/io.h>, on a second line below #define BUILDIO(bwl,bw,type) into the definition of static inline void out##bwl##_local() That gave me a linker error in the final stages of "make bzImage". Clearly arch/i386/boot/compressed/misc.c doesn't get linked directly to the rest of the kernel binary image, so it doesn't have access to the kernel's symbols. I solved that by making a clipboard copy of the whole huge BUILDIO "template" macro definition and wrapping the first copy in an #ifndef SKIP_STACK_DUMP and I only defined SKIP_STACK_DUMP in compressed/misc.c to avoid the linking problem...
Much to my amazement, this time it worked, and I was even more amazed to find out, that in fact Rene Herman was right :-)))
The poke is indeed performed by a function called ns558_init and it's indeed related to the generic game port.
What I missed in the menuconfig was this entry:
Device Drivers --> Input device support --> Hardware I/O ports --> Gameport support --> Classic ISA and PnP gameport support
Also known as CONFIG_GAMEPORT_NS558, which enables compilation of drivers/input/gameport/ns558.c
It's always fun to learn about multiple menuconfig entries for the same piece hardware or functionality in general :-)
Thanks to all those who replied, thanks for your time, and have a nice, productive day :-)
Frank Rysanek
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