On Fri 2008-02-08 13:02:57, H. Peter Anvin wrote: > Pavel Machek wrote: >> On Fri 2008-02-08 17:23:15, Rafael J. Wysocki wrote: >>> On Friday, 8 of February 2008, Pavel Machek wrote: >>>> Hi! >>> Hi, >>> >>>>>> I really need the entry point to be at offset 0, so that I can get >>>>>> pointers to my data. I could not figure out how to do it any other >>>>>> way. And if 0 is taken, I thought I'd put header at the end. >>>>>> >>>>> Why not just put the structure at 0, and put pointers in the structure >>>>> to everything else you need? >>>> segments:offsets rear its ugly head here. I need %ds to point to my >>>> data, and the way to do it is copy it from %cs; that needs start to be >>>> at 0. >>> Hm, why exactly is that necessay? >> >> It is not _neccessary_. Try to come up with another method that gets >> relocations right. I could not :-(. >> >> (Actually, putting table at the offset 0 and short jump at beggining >> of the table would probably do the trick. But that still keeps code at >> offset 0 :-). > > Why not just put a pointer to the start of the code in the table, and make > an indirect call to it? Indirect call from where? BIOS jumps to address you provide. > Where is this code? arch/x86/kernel/acpi/realmode/wakeup.S BIOS jumps to wakeup_code. With CS=something, IP=0. If wakeup code is at other address than zero, I'll not be able to easily address data below it. Pavel .globl wakeup_header wakeup_header: ... realmode_flags: .long 0 signature: .long 0x51ee1111 ... .text .globl _start .code16 wakeup_code: _start: cli cld /* Set up segments */ movw %cs,%ax movw %ax,%ds movw %ax,%es movw %ax,%ss ... /* Check header signature... */ movl signature, %eax cmpl $0x51ee1111, %eax jne bogus_real_magic Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
