linux-kernel - Re: [RFC v2 3/7] firmware: port built-in section to linker table

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Message-ID: <CAB=NE6WRr7XtRRLW=rdQx187-K9WgNMT+BAFyw3urd_Tgsz6fg@mail.gmail.com>
Date:	Fri, 29 Apr 2016 12:24:36 -0700
From:	"Luis R. Rodriguez" <mcgrof@...nel.org>
To:	James Bottomley <James.Bottomley@...senpartnership.com>,
	Kees Cook <keescook@...omium.org>
Cc:	David Woodhouse <dwmw2@...radead.org>,
	"Luis R. Rodriguez" <mcgrof@...nel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
	X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Andy Lutomirski <luto@...capital.net>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	David Vrabel <david.vrabel@...rix.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Michael Brown <mcb30@...e.org>,
	Juergen Gross <jgross@...e.com>,
	Ming Lei <ming.lei@...onical.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Arnd Bergmann <arnd@...db.de>, linux-arch@...r.kernel.org,
	Russell King <linux@....linux.org.uk>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	jbaron@...mai.com, ananth@...ibm.com,
	anil.s.keshavamurthy@...el.com, David Miller <davem@...emloft.net>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	"xen-devel@...ts.xensource.com" <xen-devel@...ts.xensource.com>
Subject: Re: [RFC v2 3/7] firmware: port built-in section to linker table

On Tue, Mar 1, 2016 at 9:54 AM, Luis R. Rodriguez <mcgrof@...nel.org> wrote:
> On Tue, Mar 01, 2016 at 08:10:24AM -0800, James Bottomley wrote:
>> On Mon, 2016-02-29 at 10:12 +0000, David Woodhouse wrote:
>> > On Fri, 2016-02-19 at 05:45 -0800, Luis R. Rodriguez wrote:
>> > > This ports built-in firmware to use linker tables,
>> > > this replaces the custom section solution with a
>> > > generic solution.
>> > >
>> > > This also demos the use of the .rodata (SECTION_RO)
>> > > linker tables.
>> > >
>> > > Tested with 0 built-in firmware, 1 and 2 built-in
>> > > firmwares successfully.
>> >
>> > I think we'd do better to rip this support out entirely. It just
>> > isn't needed; firmware can live in an initramfs and don't even need
>> > *any* actual running userspace support to load it from there these
>> > days, do we?
>>
>> We have lots of SCSI drivers with built in firmware.  The obvious
>> examples are 53c700, aic7xxx and aic79xx.  For them, we actually have
>> the firmware compilers in tree.  The firmware model they use just isn't
>> amenable to the firmware loader: they're not monolithic blobs, it's a
>> set of firmware scripts we use to handle particular operations before
>> giving control back to the host, so the firmware and the driver are
>> very much symbiotic.
>
> I'm in the process of doing some other cleanups with the firmware_class
> stuff so that odd requirements get supported but clean interfaces are
> also not hampered by these odd requirements, so I'll take a look at
> this later. If you have other oddball firmware requirements please
> let me know so I can also keep in mind.
>
>> On the other hand, I don't think any of them uses firmware sections, so
>> it's not an argument for not ripping out this type.
>
> Thanks for confirming. I'll rip this out.

Just a heads up, I've put the removal through 0-day without issues,
I'll be folding the removal into another series of changes for the
firmware API which should help compartmentalize the user mode helper
stuff as well.

 Luis