try the handle buffer in reverse order looking for plan9.ini
to find plan9 partition (9fat). when that fails, we'll default
to the first handle which should be the esp.
instead of including kernel and config in the efi
fat image, we can just include the loaders and
read the plan9.ini and kernel from iso filesystem
just like the bios loaders.
having the memconf() (*e820=) last clutters the screen.
do it first, so we can read *acpi= and *bootscreen=
prints.
we want to continue using tftp even when the /cfg/pxe/$ether
file is not found. only when we detect no pxe/dhcp session,
then we switch to local filesystem (non-network boot).
smart boot manager has a "FAT" signature in its mbr causing
9bootfat to "detect" it as a fat filesystem and then fails
to find plan9.ini.
there shouldnt be a fat filesystem on harddrives at block 0, only
on floppy drives. but some bioses use floppy drive numbers
for usb harddrives so still check for a partition table.
thanks aap for debugging this.
always look for 9fat in plan9 partition even tho the partition
is *not* maked active. marking partitions active is not
recommended anymore with grub so this makes life easier for
some people. multiple plan9 partitions on a single drive
is not supported.
have to copy partition table as buf gets trashed when reading
first block of fat partition. it worked only when the first
fat partition found (the one marked active) was the right one,
but conffat() can fail.
pbs failed to load (silently loading garbage) 9BOOTFAT from start
cluster beyond FFFF because we ignored the low word from the
directory entry. now taking the high 16 bit of the directory's
start cluster into account.
send ACK reply for duplicate data packets in case our ack response
got lost. make sure packets are in sequence and ignore out of
oder packets (except the ones we'v already acked).
