[PATCH] kexec: Add --lite option
james.morse at arm.com
Mon Dec 7 05:16:06 PST 2015
On 07/12/15 11:48, Pratyush Anand wrote:
>> 1) When we execute kexec() system call in first kernel, at that time it
>> calculates sha256 on all the binaries . It take almost un-noticeable time
>> (less than a sec) there.
>> 2) When purgatory is executed then it re-calculates sha256 using same routines
>>  on same binary data as that of case (1). But, now it takes 10-20 sec
>> (depending of size of binaries)?
>> Why did not it take same time with O2 + D-cache enabled? I think, we should be
>> able to achieve same time in second case as well. What is missing?
I haven't benchmarked this, but:
util_lib/sha256.c contains calls out to memcpy().
In your case 1, this will use the glibc version. In case 2, it will use
the version implemented in purgatory/string.c, which is a byte-by-byte copy.
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