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kernel: ignore last page at the top of virtual kernel address space for xalloc()

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avoding kernel address -BY2PG because of end pointer wrapping to zero.
This commit is contained in:
cinap_lenrek 2015-06-19 02:45:58 +02:00
parent cb2a55aeb3
commit 1bd4c243ad
1 changed files with 4 additions and 2 deletions
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6
sys/src/9/port/xalloc.c
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@ -71,8 +71,10 @@ xinit(void)
/* first give to kernel */
if(n > 0){
m->kbase = (uintptr)KADDR(m->base);
m->klimit = (uintptr)KADDR(m->base+size-1)+1;
xhole(m->base, size);
m->klimit = (uintptr)m->kbase+size;
if(m->klimit == 0)
m->klimit = (uintptr)-BY2PG;
xhole(m->base, m->klimit - m->kbase);
kpages -= n;
}
/* if anything left over, give to user */