[syslinux] Checking CRC (of bzImage) before loading

[H. Peter Anvin]

On 03/19/2014 01:30 PM, Gene Cumm wrote:
> On Wed, Mar 19, 2014 at 4:16 PM, Mau Z <zmau1962 at gmail.com> wrote:
>> Hi,
>>
>> I am wondering how to implement the following customer's requirement :
>> The system is a stand alone embedded system with no operator (with Linux).
>> There is one SSD for the system's usage (and that is where the system loads
>> from).
>>
>> The requirement is to have a duplication of the Linux Image, and that
>> syslinux should calculate CRC of "the first image" (say bzImage_1).
>> If the CRC is correct then load the image, if the CRC is not correct, than
>> syslinux should try "the other image" (say bzImage_2).
>> If even that is no good do nothing.
>>
>> Any suggestions as to how to implement the requirement ?
> 
> A custom COM32 module.  Look at ifcpu.c32 for an example of an if-else
> module and the crypto functions in com32/util/
> 

Or we could make the Linux loader (load_linux.c) throw an error on a bad
CRC, which is probably a good idea anyway.  Then the ONERROR option can
be used for the fallback.

	-hpa