qemu broke booting of old RedHat floppies

[Michael Tokarev]

As someone noticed on IRC, old (2.x) RedHat floppies does not boot
in current qemu.  When qemu is booted from floppy image at
 https://archive.org/details/RedHatLinuxBootDisk521998
(download the "ISO image" link there, it really is an 1.44 floppy),
seabios says Boot failed and that's it.

I run git bisect with it, knowing that qemu 2.1 works fine, and
it pointed out to this commit which is oldish qemu-2.5+:

commit 4812fa27fa75bce89738a82a191755853dd88408
Author: John Snow <jsnow@redhat.com>
Date:   Fri Jan 22 15:51:05 2016 -0500

    fdc: change auto fallback drive for ISA FDC to 288

    The 2.88 drive is more suitable as a default because
    it can still read 1.44 images correctly, but the reverse
    is not true.

    Since there exist virtio-win drivers that are shipped on
    2.88 floppy images, this patch will allow VMs booted without
    a floppy disk inserted to later insert a 2.88MB floppy and
    have that work.

    This patch has been tested with msdos, freedos, fedora,
    windows 8 and windows 10 without issue: if problems do
    arise for certain guests being unable to cope with 2.88MB
    drives as the default, they are in the minority and can use
    type=144 as needed (or insert a proper boot medium and omit
    type=144/288 or use type=auto) to obtain different drive types.

    As icing, the default will remain auto/144 for any pre-2.6
    machine types, hopefully minimizing the impact of this change
    in legacy hw to basically zero.

    Reviewed-by: Eric Blake <eblake@redhat.com>
    Signed-off-by: John Snow <jsnow@redhat.com>
    Message-id: 1453495865-9649-13-git-send-email-jsnow@redhat.com

Now, I don't even know where to put that "type=144/288/auto" thing,
I tried this:

 -drive 
file=RedHatLinuxBootDisk521998.disk1of1.img,if=floppy,format=raw,type=144

but it says that format=raw does not support "type=144" option.

And it's even more: I don't remember which size should be an 1.44Mb floppy :))
The file size of that image is 1492992 bytes which does not look like it is of
standard size, but I can't find which size it should be.

Thanks!

/mjt