Mad idea: grub-fuse

Mad idea: grub-fuse

[Colin Watson]

os-prober mounts filesystems using Linux's filesystem drivers. This of
course means that we have to go to special lengths to avoid replaying
journals (we don't yet, but we should), we have to load huge piles of
filesystem modules, etc.

Today's crazy idea was to implement a FUSE wrapper for grub-fstest,
thereby providing a read-only filesystem mount using GRUB's filesystem
drivers. There would be lots of things you probably wouldn't be able to
do this way, but it would be enough to support os-prober (which could of
course only use this optionally, but even so).

I can't decide whether or not this is a terrible idea, so I'm sending
mail in case somebody thinks it's a good idea and wants to run with it.
:-)

-- 
Colin Watson                                       [cjwatson@ubuntu.com]

Re: Mad idea: grub-fuse

[Bean]

On Mon, Sep 7, 2009 at 5:30 PM, Colin Watson<cjwatson@ubuntu.com> wrote:
> os-prober mounts filesystems using Linux's filesystem drivers. This of
> course means that we have to go to special lengths to avoid replaying
> journals (we don't yet, but we should), we have to load huge piles of
> filesystem modules, etc.
>
> Today's crazy idea was to implement a FUSE wrapper for grub-fstest,
> thereby providing a read-only filesystem mount using GRUB's filesystem
> drivers. There would be lots of things you probably wouldn't be able to
> do this way, but it would be enough to support os-prober (which could of
> course only use this optionally, but even so).
>
> I can't decide whether or not this is a terrible idea, so I'm sending
> mail in case somebody thinks it's a good idea and wants to run with it.
> :-)

Hi,

Actually I've considered this before. My goal is to add a mini FUSE fs
interface so that it can have read/write support in grub2 ! Of course,
the startup fs modules are still read-only, but after entering normal
mode, users can switch to the fuse driver for more functionality.

-- 
Bean

gitgrub home: http://github.com/grub/grub/
my fork page: http://github.com/bean123/grub/

Re: Mad idea: grub-fuse

[Colin Watson]

On Mon, Sep 07, 2009 at 06:07:48PM +0800, Bean wrote:
> Actually I've considered this before. My goal is to add a mini FUSE fs
> interface so that it can have read/write support in grub2 !

I'm actively uninterested in write support; in this case it would do
much more harm than good.

> Of course, the startup fs modules are still read-only, but after
> entering normal mode, users can switch to the fuse driver for more
> functionality.

The level of functionality provided by the existing filesystem modules
would be quite sufficient.

-- 
Colin Watson                                       [cjwatson@ubuntu.com]

Re: Mad idea: grub-fuse

[Bean]

On Mon, Sep 7, 2009 at 6:18 PM, Colin Watson<cjwatson@ubuntu.com> wrote:
> On Mon, Sep 07, 2009 at 06:07:48PM +0800, Bean wrote:
>> Actually I've considered this before. My goal is to add a mini FUSE fs
>> interface so that it can have read/write support in grub2 !
>
> I'm actively uninterested in write support; in this case it would do
> much more harm than good.

Hi,

It has some usage, actually both OpenFirmware and EFI have write
driver, it can be used to edit boot config files. And we don't need to
support all fs, for example, write support for fat is quite useful
while don't require much effort to implement.

>> Of course, the startup fs modules are still read-only, but after
>> entering normal mode, users can switch to the fuse driver for more
>> functionality.
>
> The level of functionality provided by the existing filesystem modules
> would be quite sufficient.

Oh I see, you mean the other way around, using the grub fs code to
implement a FUSE driver. But I don't see why not just modify os-prober
to work with grub-fstest, this is much simpler than writing a FUSE
wrapper.

-- 
Bean

gitgrub home: http://github.com/grub/grub/
my fork page: http://github.com/bean123/grub/

Re: Mad idea: grub-fuse

[Colin Watson]

On Mon, Sep 07, 2009 at 06:39:13PM +0800, Bean wrote:
> On Mon, Sep 7, 2009 at 6:18 PM, Colin Watson<cjwatson@ubuntu.com> wrote:
> > On Mon, Sep 07, 2009 at 06:07:48PM +0800, Bean wrote:
> >> Actually I've considered this before. My goal is to add a mini FUSE fs
> >> interface so that it can have read/write support in grub2 !
> >
> > I'm actively uninterested in write support; in this case it would do
> > much more harm than good.
> 
> Hi,
> 
> It has some usage, actually both OpenFirmware and EFI have write
> driver, it can be used to edit boot config files. And we don't need to
> support all fs, for example, write support for fat is quite useful
> while don't require much effort to implement.

In the case of os-prober, write support is unnecessary and I do not want
it enabled. I don't mind what's done elsewhere, but for the use case of
os-prober it absolutely must be possible to turn off write support.

> > The level of functionality provided by the existing filesystem modules
> > would be quite sufficient.
> 
> Oh I see, you mean the other way around, using the grub fs code to
> implement a FUSE driver. But I don't see why not just modify os-prober
> to work with grub-fstest, this is much simpler than writing a FUSE
> wrapper.

The changes to do that in os-prober would be sufficiently intrusive that
they simply aren't going to happen (remember that os-prober needs to
work without GRUB too). A FUSE wrapper would make it possible to just
replace the mount step, which is much easier from the client side. (Yes,
I know it's some work in GRUB, which is why this thread is labelled "Mad
idea".)

-- 
Colin Watson                                       [cjwatson@ubuntu.com]

Re: Mad idea: grub-fuse

[Michal Suchanek]

2009/9/7 Colin Watson <cjwatson@ubuntu.com>:
> On Mon, Sep 07, 2009 at 06:39:13PM +0800, Bean wrote:
>> On Mon, Sep 7, 2009 at 6:18 PM, Colin Watson<cjwatson@ubuntu.com> wrote:

>> > The level of functionality provided by the existing filesystem modules
>> > would be quite sufficient.
>>
>> Oh I see, you mean the other way around, using the grub fs code to
>> implement a FUSE driver. But I don't see why not just modify os-prober
>> to work with grub-fstest, this is much simpler than writing a FUSE
>> wrapper.
>
> The changes to do that in os-prober would be sufficiently intrusive that
> they simply aren't going to happen (remember that os-prober needs to
> work without GRUB too). A FUSE wrapper would make it possible to just
> replace the mount step, which is much easier from the client side. (Yes,
> I know it's some work in GRUB, which is why this thread is labelled "Mad
> idea".)
>

This is actually quite useful. The support for BSD filesystems on
Linux is quite poor, and it's the same the other way around but both
implement FUSE.

With FUSE grub can find kernels on any filesystems from which it can
load them regardless of the limitations of the system on which
os-prober runs.

Thanks

Michal

Re: Mad idea: grub-fuse

[Bean]

On Mon, Sep 7, 2009 at 6:51 PM, Colin Watson<cjwatson@ubuntu.com> wrote:
> On Mon, Sep 07, 2009 at 06:39:13PM +0800, Bean wrote:
>> On Mon, Sep 7, 2009 at 6:18 PM, Colin Watson<cjwatson@ubuntu.com> wrote:
>> > On Mon, Sep 07, 2009 at 06:07:48PM +0800, Bean wrote:
>> >> Actually I've considered this before. My goal is to add a mini FUSE fs
>> >> interface so that it can have read/write support in grub2 !
>> >
>> > I'm actively uninterested in write support; in this case it would do
>> > much more harm than good.
>>
>> Hi,
>>
>> It has some usage, actually both OpenFirmware and EFI have write
>> driver, it can be used to edit boot config files. And we don't need to
>> support all fs, for example, write support for fat is quite useful
>> while don't require much effort to implement.
>
> In the case of os-prober, write support is unnecessary and I do not want
> it enabled. I don't mind what's done elsewhere, but for the use case of
> os-prober it absolutely must be possible to turn off write support.

Hi,

Yep, when operated in os environment, write support need to be
disabled otherwise it could interfere with native driver and corrupt
the fs, but it's relatively safe to enable it in grub for simple fs
like fat.

-- 
Bean

gitgrub home: http://github.com/grub/grub/
my fork page: http://github.com/bean123/grub/

Re: Mad idea: grub-fuse

[Robert Millan]

On Mon, Sep 07, 2009 at 11:18:50AM +0100, Colin Watson wrote:
> On Mon, Sep 07, 2009 at 06:07:48PM +0800, Bean wrote:
> > Actually I've considered this before. My goal is to add a mini FUSE fs
> > interface so that it can have read/write support in grub2 !
> 
> I'm actively uninterested in write support; in this case it would do
> much more harm than good.

There's a thread about write support.  If we ever implement it, it will have
to be in a separate driver framework.  We can't allow write support to make
the core filesystems less stable, or prone to data corruption.

-- 
Robert Millan

  The DRM opt-in fallacy: "Your data belongs to us. We will decide when (and
  how) you may access your data; but nobody's threatening your freedom: we
  still allow you to remove your data and not access it at all."

Re: Mad idea: grub-fuse

[Vladimir 'phcoder' Serbinenko]

On Mon, Sep 7, 2009 at 11:30 AM, Colin Watson<cjwatson@ubuntu.com> wrote:
> os-prober mounts filesystems using Linux's filesystem drivers. This of
> course means that we have to go to special lengths to avoid replaying
> journals (we don't yet, but we should), we have to load huge piles of
> filesystem modules, etc.
>
> Today's crazy idea was to implement a FUSE wrapper for grub-fstest,
> thereby providing a read-only filesystem mount using GRUB's filesystem
> drivers. There would be lots of things you probably wouldn't be able to
> do this way, but it would be enough to support os-prober (which could of
> course only use this optionally, but even so).
>
> I can't decide whether or not this is a terrible idea, so I'm sending
> mail in case somebody thinks it's a good idea and wants to run with it.
> :-)
>
Actually I had this idea before but haven't had any time to implement
or think more about it. This would be useful for massive multi-OS
environment since fuse is available on many platforms but many of FS
drivers aren't. Implementing fuse wrapper for grub fs drivers is
useful. However I'm not sure if it should go to main repository - this
project isn't really about booting. I think that it's useful but
should be a separate "spin-off" project
> --
> Colin Watson                                       [cjwatson@ubuntu.com]
>
>
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> http://lists.gnu.org/mailman/listinfo/grub-devel
>



-- 
Regards
Vladimir 'phcoder' Serbinenko

Personal git repository: http://repo.or.cz/w/grub2/phcoder.git

Re: Mad idea: grub-fuse

[Michal Suchanek]

2009/9/7 Vladimir 'phcoder' Serbinenko <phcoder@gmail.com>:
> On Mon, Sep 7, 2009 at 11:30 AM, Colin Watson<cjwatson@ubuntu.com> wrote:
>> os-prober mounts filesystems using Linux's filesystem drivers. This of
>> course means that we have to go to special lengths to avoid replaying
>> journals (we don't yet, but we should), we have to load huge piles of
>> filesystem modules, etc.
>>
>> Today's crazy idea was to implement a FUSE wrapper for grub-fstest,
>> thereby providing a read-only filesystem mount using GRUB's filesystem
>> drivers. There would be lots of things you probably wouldn't be able to
>> do this way, but it would be enough to support os-prober (which could of
>> course only use this optionally, but even so).
>>
>> I can't decide whether or not this is a terrible idea, so I'm sending
>> mail in case somebody thinks it's a good idea and wants to run with it.
>> :-)
>>
> Actually I had this idea before but haven't had any time to implement
> or think more about it. This would be useful for massive multi-OS
> environment since fuse is available on many platforms but many of FS
> drivers aren't. Implementing fuse wrapper for grub fs drivers is
> useful. However I'm not sure if it should go to main repository - this
> project isn't really about booting. I think that it's useful but
> should be a separate "spin-off" project

Since we want grub use this module and at this point in time the FUSE
interface is more stable than grub interfaces I think it would be more
natural to start developing this kind of module with GRUB unless there
are some license issues. After all, grub includes other tools that are
meant for running outside of GRUB. The question remains who (if
anybody at all) writes the wrapper.

Thanks

Michal

Re: Mad idea: grub-fuse

[Bean]

On Tue, Sep 8, 2009 at 3:10 AM, Michal Suchanek<hramrach@centrum.cz> wrote:
> 2009/9/7 Vladimir 'phcoder' Serbinenko <phcoder@gmail.com>:
>> On Mon, Sep 7, 2009 at 11:30 AM, Colin Watson<cjwatson@ubuntu.com> wrote:
>>> os-prober mounts filesystems using Linux's filesystem drivers. This of
>>> course means that we have to go to special lengths to avoid replaying
>>> journals (we don't yet, but we should), we have to load huge piles of
>>> filesystem modules, etc.
>>>
>>> Today's crazy idea was to implement a FUSE wrapper for grub-fstest,
>>> thereby providing a read-only filesystem mount using GRUB's filesystem
>>> drivers. There would be lots of things you probably wouldn't be able to
>>> do this way, but it would be enough to support os-prober (which could of
>>> course only use this optionally, but even so).
>>>
>>> I can't decide whether or not this is a terrible idea, so I'm sending
>>> mail in case somebody thinks it's a good idea and wants to run with it.
>>> :-)
>>>
>> Actually I had this idea before but haven't had any time to implement
>> or think more about it. This would be useful for massive multi-OS
>> environment since fuse is available on many platforms but many of FS
>> drivers aren't. Implementing fuse wrapper for grub fs drivers is
>> useful. However I'm not sure if it should go to main repository - this
>> project isn't really about booting. I think that it's useful but
>> should be a separate "spin-off" project
>
> Since we want grub use this module and at this point in time the FUSE
> interface is more stable than grub interfaces I think it would be more
> natural to start developing this kind of module with GRUB unless there
> are some license issues. After all, grub includes other tools that are
> meant for running outside of GRUB. The question remains who (if
> anybody at all) writes the wrapper.

Hi,

I can check this out on my spare time, but for now, new menu interface
has higher priority on my todo list.

-- 
Bean

gitgrub home: http://github.com/grub/grub/
my fork page: http://github.com/bean123/grub/

Re: Mad idea: grub-fuse

[Robert Millan]

On Mon, Sep 07, 2009 at 07:49:03PM +0200, Vladimir 'phcoder' Serbinenko wrote:
> Actually I had this idea before but haven't had any time to implement
> or think more about it. This would be useful for massive multi-OS
> environment since fuse is available on many platforms but many of FS
> drivers aren't. Implementing fuse wrapper for grub fs drivers is
> useful. However I'm not sure if it should go to main repository - this
> project isn't really about booting. I think that it's useful but
> should be a separate "spin-off" project

Or a --enable-xxx flag.

-- 
Robert Millan

  The DRM opt-in fallacy: "Your data belongs to us. We will decide when (and
  how) you may access your data; but nobody's threatening your freedom: we
  still allow you to remove your data and not access it at all."