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[build] Pad .rom, .dsk, and .hd images to 512-byte boundaries
QEMU will silently round down a disk or ROM image file to the nearest
512 bytes.  Fix by always padding .rom, .dsk and .hd images to the
nearest 512-byte boundary.

Originally-fixed-by: Stefan Hajnoczi <stefanha@gmail.com>
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Michael Brown committed Apr 16, 2009
1 parent b363d19 commit 7741546
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Showing 7 changed files with 54 additions and 21 deletions.
4 changes: 2 additions & 2 deletions contrib/bochs/README.qemu
Expand Up @@ -47,13 +47,13 @@ To get qemu running is fairly simple:

8. Build gPXE floppy disk images and pad to 1.44MB
pushd ../../src
make bin/rtl8139.pdsk
make bin/rtl8139.dsk
popd

9. Start qemu
./qemu/i386-softmmu/qemu -L qemu/pc-bios \
-net nic,model=rtl8139 -net tap,ifname=tap0 \
-boot a -fda ../../src/bin/rtl8139.pdsk
-boot a -fda ../../src/bin/rtl8139.dsk

You should see qemu start up, load up gPXE and attempt to boot from
the network.
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1 change: 1 addition & 0 deletions src/Makefile
Expand Up @@ -35,6 +35,7 @@ PARSEROM := $(PERL) ./util/parserom.pl
MAKEROM := $(PERL) ./util/makerom.pl
SYMCHECK := $(PERL) ./util/symcheck.pl
SORTOBJDUMP := $(PERL) ./util/sortobjdump.pl
PADIMG := $(PERL) ./util/padimg.pl
NRV2B := ./util/nrv2b
ZBIN := ./util/zbin
ELF2EFI32 := ./util/elf2efi32
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1 change: 1 addition & 0 deletions src/Makefile.housekeeping
Expand Up @@ -724,6 +724,7 @@ define media_template
@$(ECHO_E) '$$(BIN)/%.$(1) : $$(BIN)/%.$(1).zbin' \
'\n\t$$(QM)$(ECHO) " [FINISH] $$@"' \
'\n\t$$(Q)$$(CP) $$< $$@' \
'\n\t$$(Q)$$(PAD_$(1))' \
'\n\t$$(Q)$$(FINALISE_$(1))' \
> $(2)

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7 changes: 0 additions & 7 deletions src/arch/i386/Makefile
Expand Up @@ -114,13 +114,6 @@ NON_AUTO_MEDIA += fd0
$(Q)dd if=$< bs=512 conv=sync of=/dev/fd0
$(Q)sync

# rule to create padded disk images
NON_AUTO_MEDIA += pdsk
%pdsk : %dsk
$(QM)$(ECHO) " [DSKPAD] $@"
$(Q)cp $< $@
$(Q)$(PERL) ./util/dskpad.pl $@

# Add NON_AUTO_MEDIA to the media list, so that they show up in the
# output of "make"
#
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6 changes: 6 additions & 0 deletions src/arch/i386/Makefile.pcbios
Expand Up @@ -27,6 +27,12 @@ MEDIA += raw
MEDIA += com
MEDIA += exe

# Padding rules
#
PAD_rom = $(PADIMG) --blksize=512 --byte=0xff $@
PAD_dsk = $(PADIMG) --blksize=512 $@
PAD_hd = $(PADIMG) --blksize=512 $@

# rule to make a non-emulation ISO boot image
NON_AUTO_MEDIA += iso
%iso: %lkrn util/geniso
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12 changes: 0 additions & 12 deletions src/util/dskpad.pl

This file was deleted.

44 changes: 44 additions & 0 deletions src/util/padimg.pl
@@ -0,0 +1,44 @@
#!/usr/bin/perl -w

use strict;
use warnings;
use Getopt::Long;
use Fcntl;

my $verbosity = 0;
my $blksize = 512;
my $byte = 0;

my $opts = {
'verbose|v+' => sub { $verbosity++; },
'quiet|q+' => sub { $verbosity--; },
'blksize|s=o' => sub { $blksize = $_[1]; },
'byte|b=o' => sub { $byte = $_[1]; },
};

Getopt::Long::Configure ( 'bundling', 'auto_abbrev' );
GetOptions ( { map { /^(\w+)/; $1 => $opts->{$_} } keys %$opts }, keys %$opts )
or die "Could not parse command-line options\n";

while ( my $filename = shift ) {
die "$filename is not a file\n" unless -f $filename;
my $oldsize = -s $filename;
my $newsize = ( ( $oldsize + $blksize - 1 ) & ~( $blksize - 1 ) );
my $padsize = ( $newsize - $oldsize );
next unless $padsize;
if ( $verbosity >= 1 ) {
printf "Padding %s from %d to %d bytes with %d x 0x%02x\n",
$filename, $oldsize, $newsize, $padsize, $byte;
}
if ( $byte ) {
sysopen ( my $fh, $filename, ( O_WRONLY | O_APPEND ) )
or die "Could not open $filename for appending: $!\n";
syswrite $fh, ( chr ( $byte ) x $padsize )
or die "Could not append to $filename: $!\n";
close ( $fh );
} else {
truncate $filename, $newsize
or die "Could not resize $filename: $!\n";
}
die "Failed to pad $filename\n" unless -s $filename == $newsize;
}

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