Date: Tue, 24 Nov 2015 18:15:29 -0800 From: John Baldwin <jhb@freebsd.org> To: freebsd-hackers@freebsd.org Cc: Rui Paulo <rpaulo@me.com>, Ganael Laplanche <ganael.laplanche@corp.ovh.com>, Emmanuel Vadot <manu@bidouilliste.com>, 'Warner Losh' <imp@bsdimp.com> Subject: Re: EFI Variables Message-ID: <1547195.8ivBxpzumr@ralph.baldwin.cx> In-Reply-To: <1446064708.28809.77.camel@me.com> References: <6ce779725aab266bc85e92f0ee2186b6@megadrive.org> <201510280727.19357.ganael.laplanche@corp.ovh.com> <1446064708.28809.77.camel@me.com>
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On Wednesday, October 28, 2015 01:38:28 PM Rui Paulo wrote: > On Wed, 2015-10-28 at 07:27 +0100, Ganael Laplanche wrote: > > On Tuesday, October 27, 2015 07:24:23 PM Emmanuel Vadot wrote: > > > > Hi Emmanuel, > > > > > I'm currently hacking around the loader.efi > > > > Great :) > > > > > I've also added the list and get command to the not working > > > "nvram" > > > command. > > > > I had myself posted a PR to fix that command as well as add a verbose > > switch > > and the ability to specify a variable name, see : > > > > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=202614 > > > > > For the "set" subcommand I think that the best way to handle it > > > is : > > > "nvram set myvar data" -> This will set the variable myvar to > > > data with > > > the freebsd guid (if there is any) > > > > > > and > > > > > > "nvram set myvar guid data" -> This will force the guid to <guid> > > > > It can be useful to set variables containing *strings*, but will > > hardly handle > > binary stuff :/ > > > > I am not sure whether it should be the loader's job to set > > variables... I can > > think of changing the boot order, but it may be difficult to get it > > right by > > hand and would probably require an upper-level tool, such as > > efibootmgr on > > Linux. > > > > > I'll look tomorrow how to access efivars once the kernel is > > > booted so > > > we can set some from some userland tool (especially the boot > > > related > > > one). > > > > Yes, this is interesting as the current kernel (amd64) does not > > provide access > > to EFI variables at all. > > > > 10.x/ia64 provided access to EFI variables through libefi(3) and > > io(4). It > > should be possible to import that code to other archs too, but you'll > > have to > > save the entry point to the Runtime Services Tables and maybe set a > > Virtual > > Address Map too (not sure about that point). > > > > It would be nice to set some EFI variables in the loader, but you can't > expect to handle binary data from the loader. Like you said, we need a > special tool to change EFI variables on a system already running > FreeBSD. I belive Warner has been working on adding more support for EFI runtime services to FreeBSD multiuser which might permit this. -- John Baldwin
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