On Fri, Jan 23, 2015 at 1:45 AM, Kuzmichev Viktor
<[email protected]> wrote:
Hello Stefan,
Thank you for the tip, I'm currently looking into that. But I'm
still not
sure how to specify the load address. My guess is that I should
edit the
linking script properly to do it. By default it looks as follows
(memtest.lds):
OUTPUT_FORMAT("elf32-i386");
OUTPUT_ARCH(i386);
ENTRY(_start);
SECTIONS {
. = 0x10000;
_start = . ;
.data : {
*(.data)
}
}
And here is the output of 'readelf -a memtest' command:
ELF Header:
Magic: 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00
Class: ELF32
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: EXEC (Executable file)
Machine: Intel 80386
Version: 0x1
Entry point address: 0x10000
Start of program headers: 52 (bytes into file)
Start of section headers: 239496 (bytes into file)
Flags: 0x0
Size of this header: 52 (bytes)
Size of program headers: 32 (bytes)
Number of program headers: 1
Size of section headers: 40 (bytes)
Number of section headers: 3
Section header string table index: 2
Section Headers:
[Nr] Name Type Addr Off Size ES
Flg Lk
Inf Al
[ 0] NULL 00000000 000000 000000
00 0
0 0
[ 1] .data PROGBITS 00010000 010000 02a774 00
WA 0 0
1
[ 2] .shstrtab STRTAB 00000000 03a774 000011
00 0
0 1
Key to Flags:
W (write), A (alloc), X (execute), M (merge), S (strings)
I (info), L (link order), G (group), T (TLS), E (exclude), x
(unknown)
O (extra OS processing required) o (OS specific), p (processor
specific)
There are no section groups in this file.
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz
Flg Align
LOAD 0x000000 0x00000000 0x00000000 0x3a774 0x3a774 RW
0x200000
Section to Segment mapping:
Segment Sections...
00 .data
There is no dynamic section in this file.
There are no relocations in this file.
The decoding of unwind sections for machine type Intel 80386 is not
currently supported.
No version information found in this file.
So, the entry point is at the offset of 0x10000. But I think I should
somehow change the 'VirtAddr'. I've tried to edit the script in
different
ways, for example, I've tried to add MEMORY command and then allocate
certain sections to the regions as explained here:
https://sourceware.org/binutils/docs/ld/REGION_005fALIAS.html#REGION_005fALIAS
but haven't come to any success yet.
Are there any advices you could give me? Am I even looking in the
right
direction?
Ya. You are on the right path. I just confirmed your findings locally.
What you'd like to see is VirtAddr/PhysAddr = 0x10000 as well as
offset to be 0x10000 because that would match with .data section. Also
notice that MemSiz is 0x10000 greater than the Size of the .data
section. So when this payload is loading all memory from 0x00000 to
0x10000 is filled with zeros before the start of the program at
0x10000.
I poked around in trying to relink in different ways but it kept
loading at 0. You could hexedit the memtest elf file. Apparently there
is an 'ht editor' program. However, I couldn't for the life of me
figure it out, but I was able to make it coredump trying to figure out
how to navigate it. :/
But I just found this page:
http://dwarfdump.blogspot.com/2009/08/executable-file-editor-elf-editor.html
$ hte memtest
<hit space>
Goto 'elf/program headers'. Hit <enter>
Expand 'entry 0' with <enter>
Goto 'offset'
Hit <F4>.
Make 'offset', 'virtual address', 'physical address' all to 00010000
Make 'in file size' and 'in memory size' 00027008.
Hit <F2> to save.
Hit <F10> to quit.
Those values were based on the memtest I compiled:
$ readelf -e memtest
ELF Header:
Magic: 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00
Class: ELF32
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: EXEC (Executable file)
Machine: Intel 80386
Version: 0x1
Entry point address: 0x10000
Start of program headers: 52 (bytes into file)
Start of section headers: 225308 (bytes into file)
Flags: 0x0
Size of this header: 52 (bytes)
Size of program headers: 32 (bytes)
Number of program headers: 1
Size of section headers: 40 (bytes)
Number of section headers: 3
Section header string table index: 2
Section Headers:
[Nr] Name Type Addr Off Size ES
Flg Lk Inf Al
[ 0] NULL 00000000 000000 000000
00 0 0 0
[ 1] .data PROGBITS 00010000 010000 027008 00
WA 0 0 1
[ 2] .shstrtab STRTAB 00000000 037008 000011
00 0 0 1
Key to Flags:
W (write), A (alloc), X (execute), M (merge), S (strings)
I (info), L (link order), G (group), T (TLS), E (exclude), x
(unknown)
O (extra OS processing required) o (OS specific), p (processor
specific)
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg
Align
LOAD 0x000000 0x00000000 0x00000000 0x37008 0x37008 RW
0x200000
Section to Segment mapping:
Segment Sections...
00 .data
After the instructions above I get the following:
$ readelf -e memtest
ELF Header:
Magic: 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00
Class: ELF32
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: EXEC (Executable file)
Machine: Intel 80386
Version: 0x1
Entry point address: 0x10000
Start of program headers: 52 (bytes into file)
Start of section headers: 225308 (bytes into file)
Flags: 0x0
Size of this header: 52 (bytes)
Size of program headers: 32 (bytes)
Number of program headers: 1
Size of section headers: 40 (bytes)
Number of section headers: 3
Section header string table index: 2
Section Headers:
[Nr] Name Type Addr Off Size ES
Flg Lk Inf Al
[ 0] NULL 00000000 000000 000000
00 0 0 0
[ 1] .data PROGBITS 00010000 010000 027008 00
WA 0 0 1
[ 2] .shstrtab STRTAB 00000000 037008 000011
00 0 0 1
Key to Flags:
W (write), A (alloc), X (execute), M (merge), S (strings)
I (info), L (link order), G (group), T (TLS), E (exclude), x
(unknown)
O (extra OS processing required) o (OS specific), p (processor
specific)
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg
Align
LOAD 0x010000 0x00010000 0x00010000 0x27008 0x27008 RW
0x200000
Section to Segment mapping:
Segment Sections...
00 .data
Notice now that we're only loading the .data section at 0x10000. I
hope that helps.
Thanks in advance,
Viktor
On 20.01.2015 22:33, Stefan Reinauer wrote:
* Kuzmichev Viktor <[email protected]> [150120 14:31]:
Hello,
I'm trying to load Memtest86+ on the Mohon Peak reference board from
CBFS and it fails.
My primary payload is SeaBIOS. Memtest is added using cbfstool, so
the layout of my ROM file is as follows:
$ ./build/cbfstool build/coreboot.rom print
coreboot.rom: 8192 kB, bootblocksize 1024, romsize 8388608, offset
0x600000
alignment: 64 bytes, architecture: x86
Name Offset Type Size
cmos_layout.bin 0x600000 cmos_layout 1352
fallback/romstage 0x600580 stage 26616
fallback/ramstage 0x606dc0 stage 60446
fallback/payload 0x615a40 payload 55799
config 0x623480 raw 4323
revision 0x6245c0 raw 714
img/Memtest86+ 0x6248c0 payload 225028
(empty) 0x65b800 null 1001368
mrc.cache 0x74ffc0 (unknown) 65536
cpu_microcode_blob.bin 0x760000 microcode 83968
(empty) 0x774840 null 46936
fsp.bin 0x77ffc0 (unknown) 372736
(empty) 0x7db000 null 150424
I've tried versions 4.20 and 5.01. Memtest86+ v4.20 just hangs, here
is output of SeaBIOS trying to load it:
Trying CBFS
Booting from CBFS...
Run img/Memtest86+
Segment 41544144 194420@0xffe24920 -> 194420@0x00000000
No compression
And then nothing. Memtest86+ v5.01 goes a bit further, SeaBIOS finds
its entry point:
Trying CBFS
Booting from CBFS...
Run img/Memtest86+
Segment 41544144 224972@0xffe24920 -> 224972@0x00000000
No compression
Calling addr 0x00010000
It looks like in both cases memtest86+ is loaded at address
0x00000000
which will overwrite a bunch of memory, including the coreboot
tables.
Looks like the memtest86+ elf binary needs to specify a load address.
Stefan
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