Date: Wed, 15 Feb 2012 21:32:06 +0000 (UTC) From: Jung-uk Kim <jkim@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r231781 - head/sys/amd64/amd64 Message-ID: <201202152132.q1FLW6kd082678@svn.freebsd.org>
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Author: jkim Date: Wed Feb 15 21:32:05 2012 New Revision: 231781 URL: http://svn.freebsd.org/changeset/base/231781 Log: Some BIOSes are known for corrupting low 64KB between suspend and resume. Mask off the first 16 pages unless we appear to be running in a VM. This address may be overridden by 'hw.physmem.start' tunable from loader. Note Linux used to have a BIOS quirk table for this issue but it seems they made it default recently. Modified: head/sys/amd64/amd64/machdep.c Modified: head/sys/amd64/amd64/machdep.c ============================================================================== --- head/sys/amd64/amd64/machdep.c Wed Feb 15 21:20:58 2012 (r231780) +++ head/sys/amd64/amd64/machdep.c Wed Feb 15 21:32:05 2012 (r231781) @@ -1381,7 +1381,7 @@ getmemsize(caddr_t kmdp, u_int64_t first { int i, physmap_idx, pa_indx, da_indx; vm_paddr_t pa, physmap[PHYSMAP_SIZE]; - u_long physmem_tunable, memtest; + u_long physmem_start, physmem_tunable, memtest; pt_entry_t *pte; struct bios_smap *smapbase, *smap, *smapend; u_int32_t smapsize; @@ -1469,8 +1469,19 @@ getmemsize(caddr_t kmdp, u_int64_t first /* * Size up each available chunk of physical memory. + * + * XXX Some BIOSes corrupt low 64KB between suspend and resume. + * By default, mask off the first 16 pages unless we appear to be + * running in a VM. */ - physmap[0] = PAGE_SIZE; /* mask off page 0 */ + physmem_start = (vm_guest > VM_GUEST_NO ? 1 : 16) << PAGE_SHIFT; + TUNABLE_ULONG_FETCH("hw.physmem.start", &physmem_start); + if (physmem_start < PAGE_SIZE) + physmap[0] = PAGE_SIZE; + else if (physmem_start >= physmap[1]) + physmap[0] = round_page(physmap[1] - PAGE_SIZE); + else + physmap[0] = round_page(physmem_start); pa_indx = 0; da_indx = 1; phys_avail[pa_indx++] = physmap[0];
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