Messages in this thread | | | Date | Tue, 12 Jun 2012 13:45:29 -0600 | From | Thavatchai Makphaibulcboke <> | Subject | Re: [PATCH v2] lib/decompress_unxz.c: removing all memory helper functions |
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On 06/12/2012 11:40 AM, Joe Perches wrote: > On Tue, 2012-06-12 at 10:30 -0700, H. Peter Anvin wrote: >> On 06/12/2012 10:26 AM, Nicolas Pitre wrote: >>> >>> Instead of copying, maybe this would be much better to make the content >>> of lib/string.c usable in a pre-boot environment. > >> Not sure about that... a lot of it is #ifndef __HAVE_ARCH_* and you >> *really* want those optimizations on some arches. > > Can __weak be used? >
lib/string.c contains a lot of stuff that are not needed in preboot, and would increase the kernel image size. I'm not sure if we will be able to make it usable in pre-boot and only bringing in what is needed by preboot, withtut unnecessarily complicated lib/string.c.
Thanks Joe for the suggestion. I guess we could remove the #ifndef by renaming all arch specific mem helper functions to arch_<name>, and declaring them with a weak attribute in mem.c and let the mem.c check to see if it is provided, Here is an example for memcpy
Architecture specific,
void *arch_memcpy(void *__dest, __const void *__src, size_t __n) { ... }
lib/mem.c
extern void *arch_memcpy(void *__dest, __const void *__src, size_t __n) __attribute __((weak));
void *memcpy(void *__dest, __const void *__src, size_t __n) { if (arch_memcpy) { arch_memcpgoogly(); return; }
}
But this does not solve the memmove issue. Could we always trust arch_memcpy in all architectures? I guess the safest way would be to use memmove in string.c. Please let me know if you have any thoughts or suggestions.
Thanks, Mak.
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