[SeaBIOS] 9-segment allocator
Kevin O'Connor
kevin at koconnor.net
Sat Feb 23 22:03:32 CET 2013
SeaBIOS v1.7.0 and earlier had an allocator that would reserve memory
in the "9-segment" - memory at the end of the first 640K. (Subsequent
versions of SeaBIOS allocate ram for "low memory" in the e-segment.)
I recently revived the 9-segment code for testing purposes. I don't
plan to commit this to the SeaBIOS repo - I'm posting it here in case
there is interest. It is also available at:
https://github.com/KevinOConnor/seabios/tree/test-9segment-20130223
-Kevin
>From 3608cf00a12c33f03c8dcb3f3ba272effdf3dfb7 Mon Sep 17 00:00:00 2001
From: Kevin O'Connor <kevin at koconnor.net>
Date: Mon, 18 Feb 2013 10:45:39 -0500
Subject: [PATCH] Revive 9-segment allocator.
To: seabios at seabios.org
May be useful for testing.
Signed-off-by: Kevin O'Connor <kevin at koconnor.net>
---
src/Kconfig | 9 +++++
src/pmm.c | 113 ++++++++++++++++++++++++++++++++++++++++++++++++-----
src/post.c | 10 +++--
src/shadow.c | 4 +-
src/stacks.c | 3 +-
tools/layoutrom.py | 9 +++--
6 files changed, 131 insertions(+), 17 deletions(-)
diff --git a/src/Kconfig b/src/Kconfig
index 98a6642..c88aaec 100644
--- a/src/Kconfig
+++ b/src/Kconfig
@@ -104,6 +104,15 @@ endchoice
help
Support floppy images in coreboot flash.
+ config MALLOC_UPPERMEMORY
+ bool "Allocate memory that needs to be in first Meg above 0xc0000"
+ default y
+ help
+ Use the "Upper Memory Block" area for internal "low
+ memory" allocations. If this is not selected, the memory
+ is instead allocated between 0x90000-0xa0000 (the
+ "9-segment").
+
endmenu
menu "Hardware support"
diff --git a/src/pmm.c b/src/pmm.c
index f02cf62..829547f 100644
--- a/src/pmm.c
+++ b/src/pmm.c
@@ -174,8 +174,12 @@ static struct allocinfo_s *RomBase;
u32
rom_get_max(void)
{
- return ALIGN_DOWN((u32)RomBase->allocend - OPROM_HEADER_RESERVE
- , OPTION_ROM_ALIGN);
+ if (CONFIG_MALLOC_UPPERMEMORY)
+ return ALIGN_DOWN((u32)RomBase->allocend - OPROM_HEADER_RESERVE
+ , OPTION_ROM_ALIGN);
+ extern u8 code32init_end[];
+ u32 end = (u32)code32init_end;
+ return end > BUILD_BIOS_ADDR ? BUILD_BIOS_ADDR : end;
}
// Return the end of the last deployed option rom.
@@ -189,6 +193,11 @@ rom_get_last(void)
struct rom_header *
rom_reserve(u32 size)
{
+ if (!CONFIG_MALLOC_UPPERMEMORY) {
+ if (RomEnd + size > rom_get_max())
+ return NULL;
+ return (void*)RomEnd;
+ }
u32 newend = ALIGN(RomEnd + size, OPTION_ROM_ALIGN) + OPROM_HEADER_RESERVE;
if (newend > (u32)RomBase->allocend)
return NULL;
@@ -313,8 +322,14 @@ malloc_init(void)
// Initialize low-memory region
extern u8 varlow_start[], varlow_end[], final_varlow_start[];
memmove(final_varlow_start, varlow_start, varlow_end - varlow_start);
- addSpace(&ZoneLow, zonelow_base + OPROM_HEADER_RESERVE, final_varlow_start);
- RomBase = findLast(&ZoneLow);
+ if (CONFIG_MALLOC_UPPERMEMORY) {
+ addSpace(&ZoneLow, zonelow_base + OPROM_HEADER_RESERVE
+ , final_varlow_start);
+ RomBase = findLast(&ZoneLow);
+ } else {
+ addSpace(&ZoneLow, (void*)ALIGN_DOWN((u32)final_varlow_start, 1024)
+ , final_varlow_start);
+ }
// Add space available in f-segment to ZoneFSeg
extern u8 zonefseg_start[], zonefseg_end[];
@@ -330,13 +345,19 @@ malloc_prepboot(void)
ASSERT32FLAT();
dprintf(3, "malloc finalize\n");
- // Place an optionrom signature around used low mem area.
u32 base = rom_get_max();
- struct rom_header *dummyrom = (void*)base;
- dummyrom->signature = OPTION_ROM_SIGNATURE;
- int size = (BUILD_BIOS_ADDR - base) / 512;
- dummyrom->size = (size > 255) ? 255 : size;
memset((void*)RomEnd, 0, base-RomEnd);
+ if (CONFIG_MALLOC_UPPERMEMORY) {
+ // Place an optionrom signature around used low mem area.
+ struct rom_header *dummyrom = (void*)base;
+ dummyrom->signature = OPTION_ROM_SIGNATURE;
+ int size = (BUILD_BIOS_ADDR - base) / 512;
+ dummyrom->size = (size > 255) ? 255 : size;
+ }
+
+ // Reserve more low-mem if needed.
+ u32 endlow = GET_BDA(mem_size_kb)*1024;
+ add_e820(endlow, BUILD_LOWRAM_END-endlow, E820_RESERVED);
// Clear unused f-seg ram.
struct allocinfo_s *info = findLast(&ZoneFSeg);
@@ -357,6 +378,78 @@ malloc_prepboot(void)
/****************************************************************
+ * ebda movement
+ ****************************************************************/
+
+// Move ebda
+static int
+relocate_ebda(u32 newebda, u32 oldebda, u8 ebda_size)
+{
+ u32 lowram = GET_BDA(mem_size_kb) * 1024;
+ if (oldebda != lowram)
+ // EBDA isn't at end of ram - give up.
+ return -1;
+
+ // Do copy
+ memmove((void*)newebda, (void*)oldebda, ebda_size * 1024);
+
+ // Update indexes
+ dprintf(1, "ebda moved from %x to %x\n", oldebda, newebda);
+ SET_BDA(mem_size_kb, newebda / 1024);
+ SET_BDA(ebda_seg, FLATPTR_TO_SEG(newebda));
+ return 0;
+}
+
+// Support expanding the ZoneLow dynamically.
+static void *
+zonelow_expand(u32 size, u32 align, struct allocinfo_s *fill)
+{
+ // Make sure to not move ebda while an optionrom is running.
+ if (unlikely(wait_preempt())) {
+ void *data = allocSpace(&ZoneLow, size, align, fill);
+ if (data)
+ return data;
+ }
+
+ struct allocinfo_s *info = findLast(&ZoneLow);
+ if (!info)
+ return NULL;
+ u32 oldpos = (u32)info->allocend;
+ u32 newpos = ALIGN_DOWN(oldpos - size, align);
+ u32 bottom = (u32)info->dataend;
+ if (newpos >= bottom && newpos <= oldpos)
+ // Space already present.
+ return allocSpace(&ZoneLow, size, align, fill);
+ u16 ebda_seg = get_ebda_seg();
+ u32 ebda_pos = (u32)MAKE_FLATPTR(ebda_seg, 0);
+ u8 ebda_size = GET_EBDA(ebda_seg, size);
+ u32 ebda_end = ebda_pos + ebda_size * 1024;
+ if (ebda_end != bottom)
+ // Something else is after ebda - can't use any existing space.
+ newpos = ALIGN_DOWN(ebda_end - size, align);
+ u32 newbottom = ALIGN_DOWN(newpos, 1024);
+ u32 newebda = ALIGN_DOWN(newbottom - ebda_size * 1024, 1024);
+ if (newebda < BUILD_EBDA_MINIMUM)
+ // Not enough space.
+ return NULL;
+
+ // Move ebda
+ int ret = relocate_ebda(newebda, ebda_pos, ebda_size);
+ if (ret)
+ return NULL;
+
+ // Update zone
+ if (ebda_end == bottom) {
+ info->data = (void*)newbottom;
+ info->dataend = (void*)newbottom;
+ } else
+ addSpace(&ZoneLow, (void*)newbottom, (void*)ebda_end);
+
+ return allocSpace(&ZoneLow, size, align, fill);
+}
+
+
+/****************************************************************
* tracked memory allocations
****************************************************************/
@@ -380,6 +473,8 @@ pmm_malloc(struct zone_s *zone, u32 handle, u32 size, u32 align)
// Find and reserve space for main allocation
void *data = allocSpace(zone, size, align, &detail->datainfo);
+ if (!CONFIG_MALLOC_UPPERMEMORY && !data && zone == &ZoneLow)
+ data = zonelow_expand(size, align, &detail->datainfo);
if (!data) {
freeSpace(&detail->detailinfo);
return NULL;
diff --git a/src/post.c b/src/post.c
index 44bb0b0..70a3be6 100644
--- a/src/post.c
+++ b/src/post.c
@@ -85,17 +85,21 @@ bda_init(void)
memset(bda, 0, sizeof(*bda));
int esize = EBDA_SIZE_START;
- SET_BDA(mem_size_kb, BUILD_LOWRAM_END/1024 - esize);
u16 ebda_seg = EBDA_SEGMENT_START;
+ extern u8 final_varlow_start[];
+ if (!CONFIG_MALLOC_UPPERMEMORY)
+ ebda_seg = FLATPTR_TO_SEG(ALIGN_DOWN((u32)final_varlow_start, 1024)
+ - EBDA_SIZE_START*1024);
SET_BDA(ebda_seg, ebda_seg);
+ SET_BDA(mem_size_kb, ebda_seg / (1024/16));
+
// Init ebda
struct extended_bios_data_area_s *ebda = get_ebda_ptr();
memset(ebda, 0, sizeof(*ebda));
ebda->size = esize;
- add_e820((u32)MAKE_FLATPTR(ebda_seg, 0), GET_EBDA(ebda_seg, size) * 1024
- , E820_RESERVED);
+ add_e820((u32)ebda, BUILD_LOWRAM_END-(u32)ebda, E820_RESERVED);
// Init extra stack
StackPos = (void*)(&ExtraStack[BUILD_EXTRA_STACK_SIZE] - zonelow_base);
diff --git a/src/shadow.c b/src/shadow.c
index e971fe9..5bb1bd7 100644
--- a/src/shadow.c
+++ b/src/shadow.c
@@ -80,7 +80,9 @@ make_bios_readonly_intel(u16 bdf, u32 pam0)
wbinvd();
// Write protect roms from 0xc0000-0xf0000
- u32 romend = rom_get_last(), romtop = rom_get_max();
+ u32 romend = rom_get_last(), romtop = BUILD_BIOS_ADDR;
+ if (CONFIG_MALLOC_UPPERMEMORY)
+ romtop = rom_get_max();
int i;
for (i=0; i<6; i++) {
u32 mem = BUILD_ROM_START + i * 32*1024;
diff --git a/src/stacks.c b/src/stacks.c
index 7423939..3d49d35 100644
--- a/src/stacks.c
+++ b/src/stacks.c
@@ -456,7 +456,8 @@ finish_preempt(void)
int
wait_preempt(void)
{
- if (MODESEGMENT || !CONFIG_THREAD_OPTIONROMS || !CanPreempt)
+ if (MODESEGMENT || !CONFIG_THREAD_OPTIONROMS || !CanPreempt
+ || getesp() < 1024*1024)
return 0;
while (CanPreempt)
yield();
diff --git a/tools/layoutrom.py b/tools/layoutrom.py
index 6e1c588..d45a37e 100755
--- a/tools/layoutrom.py
+++ b/tools/layoutrom.py
@@ -238,10 +238,13 @@ def doLayout(sections):
# Determine "low memory" data positions
li.sections32low = getSectionsCategory(sections, '32low')
sec32low_end = li.sec32init_start
- final_sec32low_start = min(BUILD_BIOS_ADDR, li.sec32flat_start)
- relocdelta = final_sec32low_start - sec32low_end
- zonelow_base = final_sec32low_start - 64*1024
+ final_sec32low_end = min(BUILD_BIOS_ADDR, li.sec32flat_start)
+ relocdelta = final_sec32low_end - sec32low_end
+ zonelow_base = final_sec32low_end - 64*1024
li.zonelow_base = max(BUILD_ROM_START, alignpos(zonelow_base, 2*1024))
+ if '.bss.RomBase' not in dict([(s.name, '') for s in sections]): #XXX
+ relocdelta = 0xa0000 - sec32low_end
+ li.zonelow_base = 0x90000
li.sec32low_start, li.sec32low_align = setSectionsStart(
li.sections32low, sec32low_end, 16
, segoffset=li.zonelow_base - relocdelta)
--
1.7.11.7
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