linux-kernel - Re: [PATCH] efi: add efivars kobject to efi sysfs folder

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Date:	Thu, 04 Oct 2012 17:46:24 +0800
From:	joeyli <jlee@...e.com>
To:	Matt Fleming <matt.fleming@...el.com>
Cc:	linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
	glin@...e.com, Jeremy Kerr <jeremy.kerr@...onical.com>,
	Matthew Garrett <mjg@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Peter Jones <pjones@...hat.com>
Subject: Re: [PATCH] efi: add efivars kobject to efi sysfs folder

於 四，2012-10-04 於 09:54 +0100，Matt Fleming 提到：
> On Thu, 2012-10-04 at 10:24 +0800, Lee, Chun-Yi wrote:
> > UEFI variable filesystem need a new mount point, so this patch add
> > efivars kobject to efi_kobj for create a /sys/firmware/efi/efivars
> > folder.
> > 
> > Cc: Matt Fleming <matt.fleming@...el.com>
> > Cc: Jeremy Kerr <jeremy.kerr@...onical.com>
> > Cc: Matthew Garrett <mjg@...hat.com>
> > Cc: H. Peter Anvin <hpa@...or.com>
> > Signed-off-by: Lee, Chun-Yi <jlee@...e.com>
> > ---
> >  drivers/firmware/efivars.c |   11 +++++++++++
> >  include/linux/efi.h        |    1 +
> >  2 files changed, 12 insertions(+), 0 deletions(-)
> 
> Actually, shouldn't the new filesystem be called "efivarfs", or "efifs"
> to make it more explicit that it is a filesystem?

I used "efivars" because this folder generated by efivars. But, I like
your suggestion for use "efivarfs", it's better then "efivars".

> 
> We also need something in Documentation/filesystems/ describing the old
> EFI variable method, why it's no longer any good, and why the new
> filesystem is favoured. Does anybody have anything to add to the
> following?
> 
> diff --git a/Documentation/filesystems/00-INDEX b/Documentation/filesystems/00-INDEX
> index 8c624a1..ddf5a83 100644
> --- a/Documentation/filesystems/00-INDEX
> +++ b/Documentation/filesystems/00-INDEX
> @@ -38,6 +38,8 @@ dnotify_test.c
>  	- example program for dnotify
>  ecryptfs.txt
>  	- docs on eCryptfs: stacked cryptographic filesystem for Linux.
> +efivars.txt
> +	- info for the efivars filesystem.
>  exofs.txt
>  	- info, usage, mount options, design about EXOFS.
>  ext2.txt
> diff --git a/Documentation/filesystems/efivars.txt b/Documentation/filesystems/efivars.txt
> new file mode 100644
> index 0000000..4350c1a
> --- /dev/null
> +++ b/Documentation/filesystems/efivars.txt
> @@ -0,0 +1,16 @@
> +
> +efivars - a (U)EFI variable filesystem
> +
> +The efivars filesystem was created to address the shortcomings of
> +using entries in sysfs to maintain EFI variables. The old sysfs EFI
> +variables code only supported variables of up to 1024 bytes. This
> +limitation existed in version 0.99 of the EFI specification, but was
> +removed before any full releases. Since variables can now be larger
> +than a single page, sysfs isn't the best interface for this.
> +
> +Variables can be created, deleted and modified with the efivars
> +filesystem.
> +
> +The efivars filesystem is typically mounted like this,
> +
> +	mount -t efivars none /sys/firmware/efi/efivars
> 

The above documentation is really good!


Thanks a lot!
Joey Lee

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