[coreboot] [PATCH] v3: print current and wanted LZMA scratchpad size

[Myles Watson]

On Fri, May 23, 2008 at 1:32 PM, Carl-Daniel Hailfinger
<c-d.hailfinger.devel.2006 at gmx.net> wrote:
> On 23.05.2008 21:25, Myles Watson wrote:
>> On Fri, May 23, 2008 at 1:22 PM, Carl-Daniel Hailfinger
>> <c-d.hailfinger.devel.2006 at gmx.net> wrote:
>>
>>> Print current and wanted LZMA scratchpad size in the decompression
>>> routine. That allows people to either adjust compression parameters
>>> or scratchpad size.
>>> Having a similar check during build time would be nice.
>>>
>>> Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006 at gmx.net>
>>>
>>> Index: LinuxBIOSv3-tmp/lib/lzma.c
>>> ===================================================================
>>> --- LinuxBIOSv3-tmp/lib/lzma.c  (Revision 682)
>>> +++ LinuxBIOSv3-tmp/lib/lzma.c  (Arbeitskopie)
>>> @@ -14,6 +14,7 @@
>>>  #include "string.h"
>>>  #include "console.h"
>>>
>>> +#define LZMA_SCRATCHPAD_SIZE 15980
>>>
>>
>> What's the reason for 15980?  What's the downside to increasing it further?
>>
>
> It's the value I picked during OLPC early bringup, based on compression
> efficiency measurements correlated with stack requirements. It seemed to
> be the sweet spot on Geode back then. Besides that, v3 relies on the
> stack not to outgrow 32k IIRC, otherwise stack and printk buffer will
> corrupt each other.

I don't know enough about the state of v3 at the point of
decompression, but it seems like if you could allocate the buffer on
the heap instead of the stack, it would make this better.  I also
think that it should be an error, not a warning if it can't decompress
the next stage.

> Right now the patch is a no-op except for the better error message.

Yes.  I just thought it might be worth fixing the problem at the same
time if it was simple enough.

Acked-by: Myles Watson <mylesgw at gmail.com>

Thanks,
Myles