Cleaned up version of my 'extended BIOS' patch. This one is commented
better and much simpler to understand, and works just as well (better) as a bonus. Submitted by: bde
This commit is contained in:
Nate Williams
parent
35732dda77
commit
a390940e3f
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=18023
@ -35,7 +35,7 @@
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* SUCH DAMAGE.
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*
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* from: @(#)machdep.c 7.4 (Berkeley) 6/3/91
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* $Id: machdep.c,v 1.199 1996/08/19 20:06:52 julian Exp $
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* $Id: machdep.c,v 1.200 1996/09/01 02:16:07 nate Exp $
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*/
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#include "npx.h"
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@ -1081,39 +1081,64 @@ init386(first)
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biosextmem = rtcin(RTC_EXTLO)+ (rtcin(RTC_EXTHI)<<8);
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/*
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* Print a warning and set it to the safest value if the official
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* BIOS interface (bootblock supplied) disagrees with the
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* hackish interface used above. Eventually only the official
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* interface should be used. This is necessary for some machines
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* who 'steal' memory from the basemem for use as BIOS memory.
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* If BIOS tells us that it has more than 640k in the basemem,
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* don't believe it - set it to 640k.
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*/
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if (biosbasemem > 640) {
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printf("Preposterous RTC basemem of %dK, truncating to 640K\n",
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biosbasemem);
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biosbasemem = 640;
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}
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if (bootinfo.bi_memsizes_valid && bootinfo.bi_basemem > 640) {
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printf("Preposterous BIOS basemem of %dK, truncating to 640K\n",
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bootinfo.bi_basemem);
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bootinfo.bi_basemem = 640;
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}
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/*
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* Warn if the official BIOS interface disagrees with the RTC
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* interface used above about the amount of base memory or the
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* amount of extended memory. Prefer the BIOS value for the base
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* memory. This is necessary for machines that `steal' base
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* memory for use as BIOS memory, at least if we are going to use
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* the BIOS for apm. Prefer the RTC value for extended memory.
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* Eventually the hackish interface shouldn't even be looked at.
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*/
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if (bootinfo.bi_memsizes_valid) {
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if (bootinfo.bi_basemem != biosbasemem) {
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vm_offset_t pa, va, tmpva;
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vm_size_t size;
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unsigned *pte;
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vm_offset_t pa;
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printf("BIOS basemem (%ldK) != RTC basemem (%dK), ",
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printf(
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"BIOS basemem (%ldK) != RTC basemem (%dK), setting to BIOS value\n",
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bootinfo.bi_basemem, biosbasemem);
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printf("setting to BIOS value.\n");
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biosbasemem = bootinfo.bi_basemem;
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/*
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* XXX - Map this 'hole' of memory in the same manner
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* as the ISA_HOLE (read/write/non-cacheable), since
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* the BIOS 'fudges' it to become part of the ISA_HOLE.
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* XXX if biosbasemem is now < 640, there is `hole'
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* between the end of base memory and the start of
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* ISA memory. The hole may be empty or it may
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* contain BIOS code or data. Map it read/write so
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* that the BIOS can write to it. (Memory from 0 to
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* the physical end of the kernel is mapped read-only
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* to begin with and then parts of it are remapped.
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* The parts that aren't remapped form holes that
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* remain read-only and are unused by the kernel.
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* The base memory area is below the physical end of
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* the kernel and right now forms a read-only hole.
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* The part of it from 0 to
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* (trunc_page(biosbasemem * 1024) - 1) will be
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* remapped and used by the kernel later.)
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*
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* This code is similar to the code used in
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* pmap_mapdev, but since no memory needs to be
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* allocated we simply change the mapping.
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*/
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pa = biosbasemem * 1024;
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va = pa + KERNBASE;
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size = roundup(ISA_HOLE_START - pa, PAGE_SIZE);
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for (tmpva = va; size > 0;) {
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pte = (unsigned *)vtopte(tmpva);
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*pte = pa | PG_RW | PG_V | PG_N;
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size -= PAGE_SIZE;
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tmpva += PAGE_SIZE;
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pa += PAGE_SIZE;
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for (pa = trunc_page(biosbasemem * 1024);
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pa < ISA_HOLE_START; pa += PAGE_SIZE) {
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unsigned *pte;
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pte = (unsigned *)vtopte(pa + KERNBASE);
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*pte = pa | PG_RW | PG_V;
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}
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}
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if (bootinfo.bi_extmem != biosextmem)
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@ -1121,13 +1146,6 @@ init386(first)
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bootinfo.bi_extmem, biosextmem);
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}
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/*
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* If BIOS tells us that it has more than 640k in the basemem,
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* don't believe it - set it to 640k.
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*/
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if (biosbasemem > 640)
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biosbasemem = 640;
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/*
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* Some 386 machines might give us a bogus number for extended
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* mem. If this happens, stop now.
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@ -35,7 +35,7 @@
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* SUCH DAMAGE.
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*
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* from: @(#)machdep.c 7.4 (Berkeley) 6/3/91
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* $Id: machdep.c,v 1.199 1996/08/19 20:06:52 julian Exp $
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* $Id: machdep.c,v 1.200 1996/09/01 02:16:07 nate Exp $
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*/
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#include "npx.h"
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@ -1081,39 +1081,64 @@ init386(first)
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biosextmem = rtcin(RTC_EXTLO)+ (rtcin(RTC_EXTHI)<<8);
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/*
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* Print a warning and set it to the safest value if the official
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* BIOS interface (bootblock supplied) disagrees with the
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* hackish interface used above. Eventually only the official
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* interface should be used. This is necessary for some machines
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* who 'steal' memory from the basemem for use as BIOS memory.
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* If BIOS tells us that it has more than 640k in the basemem,
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* don't believe it - set it to 640k.
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*/
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if (biosbasemem > 640) {
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printf("Preposterous RTC basemem of %dK, truncating to 640K\n",
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biosbasemem);
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biosbasemem = 640;
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}
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if (bootinfo.bi_memsizes_valid && bootinfo.bi_basemem > 640) {
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printf("Preposterous BIOS basemem of %dK, truncating to 640K\n",
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bootinfo.bi_basemem);
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bootinfo.bi_basemem = 640;
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}
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/*
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* Warn if the official BIOS interface disagrees with the RTC
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* interface used above about the amount of base memory or the
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* amount of extended memory. Prefer the BIOS value for the base
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* memory. This is necessary for machines that `steal' base
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* memory for use as BIOS memory, at least if we are going to use
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* the BIOS for apm. Prefer the RTC value for extended memory.
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* Eventually the hackish interface shouldn't even be looked at.
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*/
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if (bootinfo.bi_memsizes_valid) {
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if (bootinfo.bi_basemem != biosbasemem) {
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vm_offset_t pa, va, tmpva;
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vm_size_t size;
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unsigned *pte;
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vm_offset_t pa;
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printf("BIOS basemem (%ldK) != RTC basemem (%dK), ",
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printf(
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"BIOS basemem (%ldK) != RTC basemem (%dK), setting to BIOS value\n",
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bootinfo.bi_basemem, biosbasemem);
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printf("setting to BIOS value.\n");
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biosbasemem = bootinfo.bi_basemem;
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/*
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* XXX - Map this 'hole' of memory in the same manner
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* as the ISA_HOLE (read/write/non-cacheable), since
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* the BIOS 'fudges' it to become part of the ISA_HOLE.
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* XXX if biosbasemem is now < 640, there is `hole'
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* between the end of base memory and the start of
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* ISA memory. The hole may be empty or it may
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* contain BIOS code or data. Map it read/write so
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* that the BIOS can write to it. (Memory from 0 to
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* the physical end of the kernel is mapped read-only
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* to begin with and then parts of it are remapped.
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* The parts that aren't remapped form holes that
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* remain read-only and are unused by the kernel.
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* The base memory area is below the physical end of
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* the kernel and right now forms a read-only hole.
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* The part of it from 0 to
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* (trunc_page(biosbasemem * 1024) - 1) will be
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* remapped and used by the kernel later.)
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*
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* This code is similar to the code used in
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* pmap_mapdev, but since no memory needs to be
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* allocated we simply change the mapping.
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*/
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pa = biosbasemem * 1024;
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va = pa + KERNBASE;
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size = roundup(ISA_HOLE_START - pa, PAGE_SIZE);
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for (tmpva = va; size > 0;) {
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pte = (unsigned *)vtopte(tmpva);
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*pte = pa | PG_RW | PG_V | PG_N;
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size -= PAGE_SIZE;
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tmpva += PAGE_SIZE;
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pa += PAGE_SIZE;
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for (pa = trunc_page(biosbasemem * 1024);
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pa < ISA_HOLE_START; pa += PAGE_SIZE) {
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unsigned *pte;
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pte = (unsigned *)vtopte(pa + KERNBASE);
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*pte = pa | PG_RW | PG_V;
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}
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}
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if (bootinfo.bi_extmem != biosextmem)
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@ -1121,13 +1146,6 @@ init386(first)
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bootinfo.bi_extmem, biosextmem);
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}
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/*
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* If BIOS tells us that it has more than 640k in the basemem,
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* don't believe it - set it to 640k.
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*/
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if (biosbasemem > 640)
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biosbasemem = 640;
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/*
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* Some 386 machines might give us a bogus number for extended
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* mem. If this happens, stop now.
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