Re: [Bochs-developers] [Patch] [BIOS] support BCV for rombios

[Kevin O'C. <ke...@ko...>]

On Sun, Dec 21, 2008 at 04:10:33AM +0000, Michael Brown wrote:
> On Sunday 21 December 2008 03:57:37 Kevin O'Connor wrote:
> > The bios that comes with kvm doesn't recheck the checksum after the
> > init function, and so it shows the rom in the network boot menu
> > anyway.  (I confirmed it was wrong under kvm bios too by dumping
> > memory and manually checksuming it.)  SeaBIOS is a bit more picky -
> > however, I think this is a bug in gpxe - it should be recalculating
> > its checksum.
> 
> gPXE does recalculate its checksum at the end of option ROM initialisation, if 
> it modifies itself (which will happen iff PMM allocation succeeds).

I'm pretty sure it is modifying itself:

$ hexdump -C 10ec8139.rom > 10ec8139.rom.hex

$ hexdump -C mem1 > mem1.hex

$ diff -u 10ec8139.rom.hex mem1.hex 
--- 10ec8139.rom.hex    2008-12-20 23:36:02.000000000 -0500
+++ mem1.hex    2008-12-20 23:39:10.000000000 -0500
@@ -5,7 +5,7 @@
 00000040  00 f2 00 00 00 00 58 00  6d 00 02 00 00 f4 00 00  |......X.m.......|
 00000050  00 00 1b 03 00 00 00 00  68 74 74 70 3a 2f 2f 65  |........http://e|
 00000060  74 68 65 72 62 6f 6f 74  2e 6f 72 67 00 67 50 58  |therboot.org.gPX|
-00000070  45 00 28 50 43 49 20 78  78 3a 78 78 2e 78 29 00  |E.(PCI xx:xx.x).|
+00000070  45 20 28 50 43 49 20 46  30 3a 30 30 2e 30 29 00  |E (PCI F0:00.0).|
 00000080  55 4e 44 49 16 70 00 00  01 02 d1 03 d8 2c d8 2c  |UNDI.p.......,.,|
 00000090  36 07 50 43 49 52 60 1e  06 0f a0 0f a8 fc 0e 1f  |6.PCIR`.........|
 000000a0  8e eb 89 fb be b2 02 31  ff e8 d3 03 e8 05 04 bf  |.......1........|
@@ -52,7 +52,7 @@
 00000330  be 7a 03 e8 49 01 bb 42  df e8 d8 00 9c 31 ff e8  |.z..I..B.....1..|
 00000340  93 01 be 7e 03 e8 37 01  9d 75 04 0e e8 32 00 2e  |...~..7..u...2..|
 00000350  66 a1 60 03 66 85 c0 74  05 2e ff 2e 60 03 cd 18  |f.`.f..t....`...|
-00000360  00 00 00 00 50 72 65 73  73 20 42 20 74 6f 20 62  |....Press B to b|
+00000360  f2 e6 00 f0 50 72 65 73  73 20 42 20 74 6f 20 62  |....Press B to b|
 00000370  6f 6f 74 20 66 72 6f 6d  20 00 2e 2e 2e 00 0a 0a  |oot from .......|
 00000380  00 0e 1f be 6d 00 31 ff  e8 f4 00 be bc 03 e8 ee  |....m.1.........|
 00000390  00 66 68 4c 52 45 54 8c  d2 89 e5 31 c0 8e d0 bc  |.fhLRET....1....|

You can generate "mem1" by launching kvm with "-option-rom
10ec8139.rom", then wait for the "Press F12 for boot menu" prompt,
then press F12, then hit ctrl+alt+2 and type "memsave 0xd0000 51712
mem1".

-Kevin