Post by Robert Peirce
Every time I run bootcamp it wants to rebuild the install flash drive.
Is there a way around that. All I want to do is change the partition
size. I'm told disk utility can't do that and the only way is to delete
and reinstall. That takes forever if you have to create the install
It turns out you CAN use the install drive but you have to be really
careful or you will screw thing up to the point where you have to
rebuild your system. I did and it took almost six hours even with a
50Mb/s download speed,
First thing is ONLY use Boot Camp Assistant to delete your old Windows
partition. It turns out there is a small Windows boot partition that
Disk Utility can't remove and I could find no other way to remove it.
Once the Windows partition is removed, Boot Camp Assistant can't do
anything. Use Boot Camp Assistant. it seems to do the job without fail
and without problems.
Use Disk Utility to create the new BOOTCAMP partition using the FAT
structure. However, it turns out Disk Utility creates what is called a
hybrid map combining MBR and GUID. Windows cannot boot into that. The
solution is a program available from Sourceforge called gdisk [must be
run as root]. It is called GPT fdisk on Sourceforge. The 'n' option in
expert mode ('x') cleans this up.
More bad news. Since 10.11, gdisk cannot be run because of something
called System Integrity Protection. You have to boot up in restore mode
(Cmd-R option) and run "csrutil disable." When everything is finished
you have to do this again and run "csrutil enable." It is possible you
can run gdisk from the recovery system directly but I haven't tried it.
If I do I will let you know what happened. It is also possible you can
just leave System Integrity Protection turned off. I will leave it to
an expert to comment on whether that is advisable or not.
Once all this is done you can insert the flash drive and boot holding
down the Option key. You will then find a windows boot device that you
can select. After that it is exactly the same as had you used Boot Camp
This appears to take a lot of time but it is faster than rebuilding the
flash dive each time. Actually, by leaving SIR disabled until you are
sure you are finished, it is even faster.