Proposal to enhance boot path selections

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It has been pointed out to me (privately) that the recent changes I
made to the biosboot and efiboot code may introduce some confusion
regarding which paths are searched for the boot code.  Particularly,
prior to the recent changes one might well use a "naked" boot command
for a primary normal boot, and use /onetbsd (or /netbsd.old or
anything with a leading slash) to request booting from a previous
kernel.

With the recent changes, specifying /onetbsd will only look for a
kernel in /onetbsd and /onetbsd.gz (both being regular files);  it
will not look in /onetbsd/kernel or /onetbsd/kernel.gz as might be
expected.

If one is accustomed to booting with the leading slash it could be
disconcerting (or worse) to not having ingrained muscle-memory boot
the old kernel as expected.

So, I propose that the attached patches be made to the path selection
code.  Simply stated, a leading slash '/' character in the specified
boot name will no longer prevent treating the boot name as a kernel
directory name.  Other embedded slash characters (and multiple leading
slashes) will still prevent using the specified name as a kernel
directory name.  So, for example, ``boot /old/netbsd'' will _not_
attempt to boot /old/netbsd/kernel or /old/netbsd/kernel.gz (with
or without the leading slash.)

I've tested this in qemu for both i38 and amd64 biosboot, and tested
on bare-metal amd64[*] efiboot, and it works well.  The changes are
very localized and affect only the command_boot() code, and that code
is affected only when an explicit argument is given to the boot
command.  A "naked" boot command is not affected by these changes.

[*] For the bare-metal testing I made sure to have a second bootable
media, just in case something broke.  I did not have to resort to the
backup.  :-)

+---------------------+--------------------------+----------------------+
| Paul Goyette (.sig) | PGP Key fingerprint:     | E-mail addresses:    |
| (Retired)           | 1B11 1849 721C 56C8 F63A | [email protected]    |
| Software Developer  | 6E2E 05FD 15CE 9F2D 5102 | [email protected]  |
| & Network Engineer  |                          | [email protected] |
+---------------------+--------------------------+----------------------+
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Content-ID: <[email protected]>
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Content-Disposition: ATTACHMENT; FILENAME=BOOTNAMES.patch

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