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[romprefix] Remove .xrom prefix

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The .xrom prefix provides an experimental mechanism for loading ROM
images greater than 64kB in size by mapping the expansion ROM BAR in
at a hopefully-unused address.  This is unreliable, and potentially
dangerous.  In particular, there is no guarantee that any PCI bridges
between the CPU and the device will respond to accesses for the
"unused" memory region that is chosen, and it is possible that the
process of scanning for the "unused" memory region may end up issuing
reads to other PCI devices.  If this ends up trampling on a register
with read side-effects belonging to an unrelated PCI device, this may
cause undefined behaviour.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2010-04-19 20:32:25 +01:00
parent 8406115834
commit 329686c026
6 changed files with 20 additions and 407 deletions
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30
src/util/makerom.pl
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@@ -130,14 +130,14 @@ sub writerom ($$) {
close(R);
}
sub checksum ($$) {
my ($romref, $romsize) = @_;
sub checksum ($) {
my ($romref) = @_;
substr($$romref, 6, 1) = "\x00";
my $sum = unpack('%8C*', substr($$romref, 0, $romsize));
my $sum = unpack('%8C*', $$romref);
substr($$romref, 6, 1) = chr(256 - $sum);
# Double check
$sum = unpack('%8C*', substr($$romref, 0, $romsize));
$sum = unpack('%8C*', $$romref);
if ($sum != 0) {
print "Checksum fails\n"
} elsif ($opts{'v'}) {
@@ -146,10 +146,10 @@ sub checksum ($$) {
}
sub makerom () {
my ($rom, $romsize, $stubsize);
my ($rom, $romsize);
getopts('3xni:p:s:v', \%opts);
$ARGV[0] or die "Usage: $0 [-s romsize] [-i ident] [-p vendorid,deviceid] [-n] [-x] [-3] rom-file\n";
getopts('3xi:p:s:v', \%opts);
$ARGV[0] or die "Usage: $0 [-s romsize] [-i ident] [-p vendorid,deviceid] [-x] [-3] rom-file\n";
open(R, $ARGV[0]) or die "$ARGV[0]: $!\n";
# Read in the whole ROM in one gulp
my $filesize = read(R, $rom, MAXROMSIZE+1);
@@ -183,16 +183,10 @@ sub makerom () {
}
# Pad with 0xFF to $romsize
$rom .= "\xFF" x ($romsize - length($rom));
# If this is a stub ROM, don't force header size to the full amount
if (!$opts{'n'}) {
if ($romsize >= 128 * 1024) {
print "Warning: ROM size exceeds extension BIOS limit\n";
}
substr($rom, 2, 1) = chr(($romsize / 512) % 256);
} else {
$stubsize = ord(substr($rom, 2, 1)) * 512;
print "Stub size is $stubsize\n" if $opts{'v'};
if ($romsize >= 128 * 1024) {
print "Warning: ROM size exceeds extension BIOS limit\n";
}
substr($rom, 2, 1) = chr(($romsize / 512) % 256);
print "ROM size is $romsize\n" if $opts{'v'};
# set the product string only if we don't have one yet
my $pnp_hdr_offset = unpack('v', substr($rom, PNP_PTR_LOC, 2));
@@ -202,7 +196,7 @@ sub makerom () {
# 3c503 requires last two bytes to be 0x80
substr($rom, MINROMSIZE-2, 2) = "\x80\x80"
if ($opts{'3'} and $romsize == MINROMSIZE);
checksum(\$rom, $opts{'n'} ? $stubsize : $romsize);
checksum(\$rom);
writerom($ARGV[0], \$rom);
}
@@ -219,7 +213,7 @@ sub modrom () {
print "$filesize bytes read\n" if $opts{'v'};
pcipnpheaders(\$rom, undef);
undiheaders(\$rom);
checksum(\$rom, ord(substr($rom, 2, 1)) * 512);
checksum(\$rom);
writerom($ARGV[0], \$rom);
}