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[pcbios] Sanity-check the INT15,e820 and INT15,e801 memory maps

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Some systems seem to report insane memory maps (particularly at POST
time).  Detect and work around some of the common failure cases.
This commit is contained in:
Michael Brown 2008-09-23 23:35:19 +01:00
parent e13d793160
commit 8b20e5d2b7
1 changed files with 33 additions and 0 deletions
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33
src/arch/i386/firmware/pcbios/memmap.c
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@ -89,6 +89,17 @@ static unsigned int extmemsize_e801 ( void ) {
DBG ( "INT 15,e801 extended memory size %d+64*%d=%d kB "
"[100000,%llx)\n", extmem_1m_to_16m_k, extmem_16m_plus_64k,
extmem, ( 0x100000 + ( ( ( uint64_t ) extmem ) * 1024 ) ) );
/* Sanity check. Some BIOSes report the entire 4GB address
* space as available, which cannot be correct (since that
* would leave no address space available for 32-bit PCI
* BARs).
*/
if ( extmem == ( 0x400000 - 0x400 ) ) {
DBG ( "INT 15,e801 reported whole 4GB; assuming insane\n" );
return 0;
}
return extmem;
}
@ -186,6 +197,28 @@ static int meme820 ( struct memory_map *memmap ) {
}
} while ( next != 0 );
/* Sanity checks. Some BIOSes report complete garbage via INT
* 15,e820 (especially at POST time), despite passing the
* signature checks. We currently check for a base memory
* region (starting at 0) and at least one high memory region
* (starting at 0x100000).
*/
if ( memmap->count < 2 ) {
DBG ( "INT 15,e820 returned only %d regions; assuming "
"insane\n", memmap->count );
return -EINVAL;
}
if ( memmap->regions[0].start != 0 ) {
DBG ( "INT 15,e820 region 0 starts at %llx (expected 0); "
"assuming insane\n", memmap->regions[0].start );
return -EINVAL;
}
if ( memmap->regions[1].start != 0x100000 ) {
DBG ( "INT 15,e820 region 1 starts at %llx (expected 100000); "
"assuming insane\n", memmap->regions[0].start );
return -EINVAL;
}
return 0;
}