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[relocate] Remove the even megabyte constraint

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iPXE is now capable of operating in odd megabytes of memory, so remove
the obsolete code enforcing an even-megabyte constraint.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown 2010-04-20 19:33:41 +01:00
parent 38cd2035ff
commit 9cf5170c30
1 changed files with 8 additions and 48 deletions
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56
src/arch/i386/core/relocate.c
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@ -32,12 +32,12 @@ extern char _etextdata[];
#define MAX_ADDR (0xfff00000UL)
/**
* Relocate Etherboot
* Relocate iPXE
*
* @v ix86 x86 register dump from prefix
* @ret ix86 x86 registers to return to prefix
*
* This finds a suitable location for Etherboot near the top of 32-bit
* This finds a suitable location for iPXE near the top of 32-bit
* address space, and returns the physical address of the new location
* to the prefix in %edi.
*/
@ -59,11 +59,7 @@ __asmcall void relocate ( struct i386_all_regs *ix86 ) {
start, end, padded_size, max_align );
/* Walk through the memory map and find the highest address
* below 4GB that etherboot will fit into. Ensure etherboot
* lies entirely within a range with A20=0. This means that
* even if something screws up the state of the A20 line, the
* etherboot code is still visible and we have a chance to
* diagnose the problem.
* below 4GB that iPXE will fit into.
*/
new_end = end;
for ( i = 0 ; i < memmap.count ; i++ ) {
@ -87,42 +83,6 @@ __asmcall void relocate ( struct i386_all_regs *ix86 ) {
} else {
r_end = region->end;
}
/* Shrink the range down to use only even megabytes
* (i.e. A20=0).
*/
if ( ( r_end - 1 ) & 0x100000 ) {
/* If last byte that might be used (r_end-1)
* is in an odd megabyte, round down r_end to
* the top of the next even megabyte.
*
* Make sure that we don't accidentally wrap
* r_end below 0.
*/
if ( r_end >= 1 ) {
r_end = ( r_end - 1 ) & ~0xfffff;
DBG ( "...end truncated to %lx "
"(avoid ending in odd megabyte)\n",
r_end );
}
} else if ( ( r_end - size ) & 0x100000 ) {
/* If the last byte that might be used
* (r_end-1) is in an even megabyte, but the
* first byte that might be used (r_end-size)
* is an odd megabyte, round down to the top
* of the next even megabyte.
*
* Make sure that we don't accidentally wrap
* r_end below 0.
*/
if ( r_end >= 0x100000 ) {
r_end = ( r_end - 0x100000 ) & ~0xfffff;
DBG ( "...end truncated to %lx "
"(avoid starting in odd megabyte)\n",
r_end );
}
}
DBG ( "...usable portion is [%lx,%lx)\n", r_start, r_end );
/* If we have rounded down r_end below r_ start, skip
@ -133,19 +93,19 @@ __asmcall void relocate ( struct i386_all_regs *ix86 ) {
continue;
}
/* Check that there is enough space to fit in Etherboot */
/* Check that there is enough space to fit in iPXE */
if ( ( r_end - r_start ) < size ) {
DBG ( "...too small (need %lx bytes)\n", size );
continue;
}
/* If the start address of the Etherboot we would
/* If the start address of the iPXE we would
* place in this block is higher than the end address
* of the current highest block, use this block.
*
* Note that this avoids overlaps with the current
* Etherboot, as well as choosing the highest of all
* viable blocks.
* iPXE, as well as choosing the highest of all viable
* blocks.
*/
if ( ( r_end - size ) > new_end ) {
new_end = r_end;
@ -153,7 +113,7 @@ __asmcall void relocate ( struct i386_all_regs *ix86 ) {
}
}
/* Calculate new location of Etherboot, and align it to the
/* Calculate new location of iPXE, and align it to the
* required alignemnt.
*/
new_start = new_end - padded_size;