xCAT/xNBA
2
0
Fork 0
mirror of https://github.com/xcat2/xNBA.git synced 2024-11-23 01:51:58 +00:00
Code Issues Projects Releases Wiki Activity

[romprefix] Use smaller PMM allocations if possible

Browse Source 
The only way that PMM allows us to request a block in a region with
A20=0 is to ask for a block with an alignment of 2MB.  Due to the PMM
API design, the only way we can do this is to ask for a block with a
size of 2MB.

Unfortunately, some BIOSes will hit problems if we allocate a 2MB
block.  In particular, it may not be possible to enter the BIOS setup
screen; the BIOS setup code attempts a PMM allocation, fails, and
hangs the machine.

We now try allocating only as much as we need via PMM.  If the
allocated block has A20=1, we free the allocated block, double the
allocation size, and try again.  Repeat until either we obtain a block
with A20=0 or allocation fails.  (This is guaranteed to terminate by
the time we reach an allocation size of 2MB.)
This commit is contained in:
Michael Brown 2008-11-11 20:00:13 +00:00
parent 125c6d66a8
commit 2ca2607b1b
1 changed files with 41 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

48
src/arch/i386/prefix/romprefix.S
View File

@ -14,6 +14,7 @@
#define STACK_MAGIC ( 'L' + ( 'R' << 8 ) + ( 'E' << 16 ) + ( 'T' << 24 ) )
#define PNP_GET_BBS_VERSION 0x60
#define PMM_ALLOCATE 0x0000
#define PMM_DEALLOCATE 0x0002
/* ROM banner timeout. Based on the configurable BANNER_TIMEOUT in
* config.h, but converted to a number of (18Hz) timer ticks, and
@ -290,21 +291,52 @@ pmm_scan:
movw $init_message_pmm, %si
xorw %di, %di
call print_message
/* Try to allocate 2MB block via PMM */
/* We have PMM and so a 1kB stack: preserve upper register halves */
pushal
/* Calculate required allocation size in %esi */
movzbl romheader_size, %eax
shll $9, %eax
addl $_textdata_memsz, %eax
orw $0xffff, %ax /* Ensure allocation size is at least 64kB */
bsrl %eax, %ecx
subw $15, %cx /* Round up and convert to 64kB count */
movw $1, %si
shlw %cl, %si
pmm_loop:
/* Try to allocate block via PMM */
pushw $0x0006 /* Aligned, extended memory */
pushl $0xffffffff /* No handle */
pushl $( 0x00200000 / 16 ) /* 2MB in paragraphs */
movzwl %si, %eax
shll $12, %eax
pushl %eax /* Allocation size in paragraphs */
pushw $PMM_ALLOCATE
lcall *%es:7
addw $12, %sp
/* Abort if allocation fails */
testw %dx, %dx /* %ax==0 even on success, since align>=64kB */
jz pmm_fail
/* If block has A20==1, free block and try again with twice
* the allocation size (and hence alignment).
*/
testw $0x0010, %dx
jz got_pmm
pushw %dx
pushw $0
pushw $PMM_DEALLOCATE
lcall *%es:7
addw $6, %sp
addw %si, %si
jmp pmm_loop
got_pmm: /* PMM allocation succeeded */
movw %dx, ( image_source + 2 )
movw %dx, %ax
xorw %di, %di
call print_hex_word
movw %dx, ( image_source + 2 )
testw %dx, %dx /* %ax==0 even on success, since align=2MB */
jz no_pmm
/* PMM allocation succeeded: copy ROM to PMM block */
pushal /* PMM presence implies 1kB stack */
movb $'@', %al
call print_character
movw %si, %ax
call print_hex_byte
/* Copy ROM to PMM block */
xorw %ax, %ax
movw %ax, %es
movl image_source, %edi
@ -323,6 +355,8 @@ pmm_scan:
addb %al, %bl
loop 1b
subb %bl, checksum
pmm_fail:
/* Restore upper register halves */
popal
no_pmm: