Re: Enhancing cdboot [patch for review]
- From: Giorgos Keramidas <keramida@xxxxxxxxxxxxxxx>
- Date: Tue, 09 Dec 2008 03:29:28 +0200
On Mon, 08 Dec 2008 16:29:04 -0800, Maxim Sobolev <sobomax@xxxxxxxxxxx> wrote:
Luigi Rizzo wrote:
On Mon, Dec 08, 2008 at 02:40:41PM -0800, Maxim Sobolev wrote:
Hi,...
Below please find patch that enhances cdboot with two compile-time options:
Any comments/suggestions are appreciated. If there are no objections I
would like to commit the change. The long-term goal is to make
CDBOOT_PROMPT default mode for installation CD.
http://sobomax.sippysoft.com/~sobomax/cdboot.diff
Looks good. Some comments:
Thank you for the review and comments. Please see my answers below.
1. since there is plenty of space in the cdboot sector, why don't you
make the two option always compiled in, controlling which one to
activate through flags in the bootsector itself, to be set
patching the binary sector itself using a mechanism similar to
boot0cfg.
Of course you cannot alter a cdrom after you burn it,
but it makes it easier to build CDs with one or the other defaults,
patching cdboot or the iso image itself before creating/burning it.
2. in fact, the 'silent' option could be disabled at runtime by
pressing some key (e.g. adding a short wait loop before proceeding;
if this is meant for custom, unattended CDs the extra delay should not
matter much);
Good idea, I will see if I can put that in. In fact this behavior should
have to be optional as well, since one of the uses for the "silent"
option here is to provide tamper-resistant boot process on custom
hardware.
Nice pair of features :-)
If there are no pressing space constraints maybe we can build both
options in by default, but still make them opt-out when necessary?
With a bit of makefile glue we can make it possible to compile with an
`src.conf' that includes:
WITH_CDBOOT_SILENT=1
WITHOUT_CDBOOT_PROMPT=1
This way the defaults can include support for both options, but we can
conditionally compile *out* the bits that are not needed for some custom
installation.
Something like this can define one or both of these options in CFLAGS,
depending on what `src.conf' contains:
# When CDBOOT_SILENT is set, the cdboot doesn't produce any messages except
# "Loading, please wait..." and it also passes RBX_MUTE flag to the next
# stage to silence it as well. This is intended for custom installations
# where end-user is not required to see any messages or interfere with the
# boot process.
.if ${MK_CDBOOT_SILENT} != "no"
CFLAGS+= -DCDBOOT_SILENT
.endif
# When CDBOOT_PROMPT is enabled the cdboot behaves like windows xp or vista
# cd loader, that is it reads MBR from the first hard drive in the system
# and if the MBR is bootable (i.e. drive has some other operating system
# installed on it) then it presents user with "Press any key to boot from
# CD" prompt and waits for 20 seconds. If key is not pressed then the
# control is passed to the MBR, otherwise CD is booted. This is intended for
# installation CD to allow unattended mode and also helps when installation
# CD has been unintentionally left in the drive of the machine that is set
# to boot off CD.
.if ${MK_CDBOOT_PROMPT} != "no"
CFLAGS+= -DCDBOOT_PROMPT
.endif
The defaults for ${MK_CDBOOT_XXX} will have to be explicitly set in
`src/share/mk/bsd.own.mk', near line 281:
281 #
282 # MK_* options which default to "yes".
283 #
284 .for var in \
...
But that shouldn't be a problem, AFAICT :-)
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- References:
- Enhancing cdboot [patch for review]
- From: Maxim Sobolev
- Re: Enhancing cdboot [patch for review]
- From: Luigi Rizzo
- Re: Enhancing cdboot [patch for review]
- From: Maxim Sobolev
- Enhancing cdboot [patch for review]
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