diff options
Diffstat (limited to 'sys/amd64/amd64/locore.S')
| -rw-r--r-- | sys/amd64/amd64/locore.S | 94 |
1 files changed, 76 insertions, 18 deletions
diff --git a/sys/amd64/amd64/locore.S b/sys/amd64/amd64/locore.S index bc7b854..4b6df54 100644 --- a/sys/amd64/amd64/locore.S +++ b/sys/amd64/amd64/locore.S @@ -34,7 +34,7 @@ * SUCH DAMAGE. * * from: @(#)locore.s 7.3 (Berkeley) 5/13/91 - * $Id: locore.s,v 1.29 1994/09/26 16:56:22 pst Exp $ + * $Id: locore.s,v 1.30 1994/10/01 02:56:01 davidg Exp $ */ /* @@ -125,9 +125,6 @@ _KERNend: .long 0 /* phys addr end of kernel (just after bss) */ _IdlePTD: .long 0 /* phys addr of kernel PTD */ _KPTphys: .long 0 /* phys addr of kernel page tables */ - .globl _cyloffset -_cyloffset: .long 0 /* cylinder offset from boot blocks */ - .globl _proc0paddr _proc0paddr: .long 0 /* address of proc 0 address space */ @@ -161,24 +158,93 @@ tmpstk: NON_GPROF_ENTRY(btext) movw $0x1234,0x472 /* warm boot */ jmp 1f + /* + * XXX now that we load at 1MB is this still really used? + */ .org 0x500 /* space for BIOS variables */ - 1: +1: /* Don't trust what the BIOS gives for eflags. */ pushl $PSL_MBO popfl /* - * pass parameters on stack (howto, bootdev, unit, cyloffset, esym) - * note: (%esp) is return address of boot - * ( if we want to hold onto /boot, it's physical %esp up to _end) + * This code is called in different ways depending on what loaded + * and started the kernel. This is used to detect how we get the + * arguments from the other code and what we do with them. + * + * Old disk boot blocks: + * (*btext)(howto, bootdev, cyloffset, esym); + * [return address == 0, and can NOT be returned to] + * [cyloffset was not supported by the FreeBSD boot code + * and always passed in as 0] + * [esym is also known as total in the boot code, and + * was never properly supported by the FreeBSD boot code] + * + * Old diskless netboot code: + * (*btext)(0,0,0,0,&nfsdiskless,0,0,0); + * [return address != 0, and can NOT be returned to] + * If we are being booted by this code it will NOT work, + * so we are just going to halt if we find this case. + * + * New uniform boot code: + * (*btext)(howto, bootdev, 0, 0, 0, &bootinfo) + * [return address != 0, and can be returned to] + * + * There may seem to be a lot of wasted arguments in here, but + * that is so the newer boot code can still load very old kernels. + */ + + /* + * The old style disk boot blocks fake a frame on the stack and + * did an lret to get here. The frame on the stack has a return + * address of 0. + */ + cmpl $0,0x00(%esp) + je 2f /* olddiskboot: */ + + /* + * We have some form of return address, so this is either the + * old diskless netboot code, or the new uniform code. That can + * be detected by looking at the 5th argument, it if is 0 we + * we are being booted by the new unifrom boot code. */ + cmpl $0,0x14(%esp) + je 1f /* newboot: */ + + /* + * Seems we have been loaded by the old diskless boot code, we + * don't stand a chance of running as the diskless structure + * changed considerably between the two, so just halt. + */ + hlt + + /* + * We have been loaded by the new uniform boot code, this kernel + * is not yet ready to handle that, so for now fix up the stack + * like a real subroutine and then return to the boot loader with + * a status of 1 to indicate this error. + */ +1: /* newboot: */ + pushl %ebp + movl %esp,%ebp + movl $1,%eax + leave + ret + + /* + * The old style disk boot. + * (*btext)(howto, bootdev, cyloffset, esym); + * cyloffset is no longer copied + * XXX Is esym still used for the end of the kernel some place??? + * for now make sure we keep a correct value in it until I + * can deterimine that. + */ +2: /* olddiskboot: */ movl 4(%esp),%eax movl %eax,_boothowto-KERNBASE movl 8(%esp),%eax movl %eax,_bootdev-KERNBASE - movl 12(%esp),%eax - movl %eax,_cyloffset-KERNBASE movl 16(%esp),%eax addl $KERNBASE,%eax movl %eax,_esym-KERNBASE @@ -200,14 +266,6 @@ NON_GPROF_ENTRY(btext) addl $KERNBASE, %eax movl %eax, _video_mode_ptr-KERNBASE -#ifdef DISKLESS /* Copy diskless structure */ - movl _nfs_diskless_size-KERNBASE,%ecx - movl 20(%esp),%esi - movl $(_nfs_diskless-KERNBASE),%edi - cld - rep - movsb -#endif #ifdef APM /* * Setup APM BIOS: |
