Re: [PATCH] x86: tidy e820 output

H. Peter Anvin
2010-09-22T23:17:01Z

On 09/22/2010 04:12 PM, David Rientjes wrote:
> On Wed, 22 Sep 2010, H. Peter Anvin wrote:
>
>>> This patch is going to break our userspace parsing scripts if you change
>>> the output format. Admittedly, we're probably one of the few users who
>>> actually parses this output, but we do have reasons to do it for our
>>> firmware. If there was some improvement being introduced here, we'd
>>> happily handle multiple regexs (we constantly add new patterns when new
>>> kernels are released), but I'm not seeing how this is better.
>>
>> Kernel messages are not an ABI or API.
>>
>> The user space API for this stuff is /sys/firmware/memmap.
>>
>
> I'm referring to using [start, start + addr - 1] in the output, like
> /sys/firmware/memmap does, as opposed to [start, start + addr]. Is it not
> valuable to include the actual e820 map in some way, especially when you
> have your own BIOS? We've always used this output since it isn't
> available later.

"The actual e820 map" contains (start, length, type) -- the end bracket
is not part of it at all. Either way, /sys/firmware/memmap does provide
the memory map as provided by the firmware through whatever means.

> Another use of this information that people may already be using it for is
> ensuring the memmap= on the command line is parsed correctly.
>
> So, again, I'm looking for the benefit here in this patch and it's not
> immediately apparent to me.

Consistency with other resources displayed seems like a major win to me.

-hpa