diff options
| author | cinap_lenrek <cinap_lenrek@felloff.net> | 2014-11-20 19:05:43 +0100 |
|---|---|---|
| committer | cinap_lenrek <cinap_lenrek@felloff.net> | 2014-11-20 19:05:43 +0100 |
| commit | 529082d34d2bafd81d5987a2ed646c3a3c88a0a2 (patch) | |
| tree | 72e78cefad3f628729ffacaec80a515bda77c27d /sys/src/9/pc64 | |
| parent | 5a6131ea0919726bee4cba03a7a5361e6ea6df92 (diff) | |
pc, pc64: preserve last KB of conventional memory (might contain bios tables)
we add new function convmemsize() that returns the size of
*usable* conventional memory that does some sanity checking
and reserves the last KB below the top of memory pointer.
this avoids lowraminit() overriding potential bios tables
and sigsearch() going off the rails looking for tables
at above 640K.
Diffstat (limited to 'sys/src/9/pc64')
| -rw-r--r-- | sys/src/9/pc64/memory.c | 30 |
1 files changed, 21 insertions, 9 deletions
diff --git a/sys/src/9/pc64/memory.c b/sys/src/9/pc64/memory.c index 349133976..cb2c15219 100644 --- a/sys/src/9/pc64/memory.c +++ b/sys/src/9/pc64/memory.c @@ -337,6 +337,24 @@ sigscan(uchar* addr, int len, char* signature) return nil; } +static uintptr +convmemsize(void) +{ + uintptr top; + uchar *bda; + + bda = KADDR(0x400); + top = ((bda[0x14]<<8) | bda[0x13])*KB; + + if(top < 64*KB || top > 640*KB) + top = 640*KB; /* sanity */ + + /* reserved for bios tables (EBDA) */ + top -= 1*KB; + + return top; +} + void* sigsearch(char* signature) { @@ -359,11 +377,9 @@ sigsearch(char* signature) return r; } } + if((r = sigscan(KADDR(convmemsize()), 1024, signature)) != nil) + return r; - if((p = ((bda[0x14]<<8)|bda[0x13])*1024) != 0){ - if((r = sigscan(KADDR(p-1024), 1024, signature)) != nil) - return r; - } /* hack for virtualbox: look in KiB below 0xa0000 */ if((r = sigscan(KADDR(0xa0000-1024), 1024, signature)) != nil) return r; @@ -375,7 +391,6 @@ static void lowraminit(void) { uintptr pa, x; - uchar *bda; /* * Initialise the memory bank information for conventional memory @@ -384,10 +399,7 @@ lowraminit(void) * the BIOS data area. */ x = PADDR(CPU0END); - bda = (uchar*)KADDR(0x400); - pa = ((bda[0x14]<<8)|bda[0x13])*KB; - if(pa > 640*KB) - pa = 640*KB; + pa = convmemsize(); if(x < pa){ mapfree(&rmapram, x, pa-x); memset(KADDR(x), 0, pa-x); /* keep us honest */ |