linux-kernel - Re: [PATCH 01/11] resource: Add System RAM resource type

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Date:	Wed, 16 Dec 2015 09:35:59 -0700
From:	Toshi Kani <toshi.kani@....com>
To:	Borislav Petkov <bp@...en8.de>
Cc:	akpm@...ux-foundation.org, linux-arch@...r.kernel.org,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCH 01/11] resource: Add System RAM resource type

On Wed, 2015-12-16 at 16:49 +0100, Borislav Petkov wrote:
> On Wed, Dec 16, 2015 at 08:44:02AM -0700, Toshi Kani wrote:
> > Besides "System RAM", which is commonly searched by multiple callers,
> > we
> > only have a few other uncommon cases:
> >  - crash.c searches for "GART", "ACPI Tables", and "ACPI Non-volatile
> > Storage".
> >  - kexec_file.c searches for "Crash kernel".
> >  - einj.c will search for "Persistent Memory".
> 
> Right, about those other types: your patchset improves the situation
> but doesn't really get rid of the strcmp() and the strings. And using
> strings to find resource types still looks yucky to me, even a week
> later. :)
> 
> So how hard is it to do:
> 
> 	region_intersects(base_addr, size, IORESOURCE_SYSTEM_RAM);
> 	region_intersects(base_addr, size, IORESOURCE_MEM,
> RES_TYPE_PERSISTENT);
> 	walk_iomem_res(RES_TYPE_GART, IORESOURCE_MEM, 0, -1, ced,
> get_gart_ranges_callback);
> 	...
> 
> and so on instead of using those silly strings?

We do not have enough bits left to cover any potential future use-cases
with other strings if we are going to get rid of strcmp() completely. 
 Since the searches from crash and kexec are one-time thing, and einj is a
R&D tool, I think we can leave the strcmp() check for these special cases,
and keep the interface flexible with any strings.

Thanks,
-Toshi
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