Hi Ahmad,
On 8/29/23 13:08, Ahmad Fatoum wrote:
On 29.08.23 12:55, Johannes Zink wrote:
On 8/29/23 12:45, Ahmad Fatoum wrote:
+lwl-$(CONFIG_CRC32_EARLY) += crc32.o
pbl-obj- is the correct prefix. lwl- means pbl- if we have PBL
support at all and obj- otherwise (for legacy systems without PBL),
while pbl-obj- is equivalent to duplicating the line once with pbl-
and once with obj-
s/pbl-obj-/obj-pbl-/ :)
Sorry, had a small brain fart here.
You didn't remove the original obj-,
so now lwl- either expands to and extra obj- or to pbl-.
obj-pbl- makes sense when you use the same symbol for both PBL and
barebox proper, but as you're introducing a new symbol, you can
leave it as lwl- or make it pbl- for explicitness.
ok. I think I won't glob it in obj-pbl, as one might want to explicitly add
crc32.o only for PBL or only for barebox-proper.
ack, gonna fix this for v2.
obj-$(CONFIG_DIGEST_SHA384_GENERIC) += sha4.o
obj-$(CONFIG_DIGEST_SHA512_GENERIC) += sha4.o
obj-y += memneq.o
diff --git a/crypto/crc32.c b/crypto/crc32.c
index 95cb2212db2b..284d39351682 100644
--- a/crypto/crc32.c
+++ b/crypto/crc32.c
@@ -22,7 +22,7 @@
#define STATIC static inline
#endif
-#ifdef CONFIG_DYNAMIC_CRC_TABLE
+#if defined(CONFIG_DYNAMIC_CRC_TABLE) && !defined(__PBL__)
You could also replace the dynamic allocation with a static array initialized
to zero. That way you can have a dynamic crc table even in PBL without affecting
image size as the BSS is not part of the image.
ack. Is this ok?
#ifdef __PBL__
static uint32_t _crc_table_memory[sizeof(uint32_t) * 256] = { 0 };
The array is 256 elements, not 1024 elements. Explicit intialization
is unnecessary.
good catch. thanks.
#endif
static void *alloc_crc_table() {
#ifdef __PBL__
return _crc_table_memory;
#else
return xmalloc(sizeof(uint32_t) * 256);
#endif
}
If so, I can change it for v2.
My idea was to drop the allocation altogether by using BSS.
If you do this, you should not need any __PBL__ checking at all.
I guess that should work indeed. Do I need to explicitly mark the array with a
prefix to force it into BSS (sorry, I am not too familiar with the barebox
linker scripts...)?
Either you have CONFIG_DYNAMIC_CRC_TABLE and the table is dynamically
filled in bss on first access or you have CONFIG_DYNAMIC_CRC_TABLE=n
and the table is already there and need not be allocated.
On a second thought, I am not sure if we want a table at all in PBL.
Do you do a lot of CRC32 computation? Maybe we should just not use
a table at all in PBL and just calculate a single crc32?
That's what Sascha did here:
2d13b856604b ("crc: Add PBL variant for crc_itu_t()")
For my specific usecase I need to check a single CRC32 once, so probably there
is the same or even more overhead to dynamically filling the Table than just
doing a single CRC32 computation. Maybe more overhead than using the
precompiled, pre-filled table, but I fully acknowledge that size matters in PBL.
I like Sascha's approach, so let me try to do a dynamic computation for the PBL
implementation in my v2 patch.
Best regards
Johannes
Let me know what you think.
Cheers,
Ahmad
Best regards
Johannes
static uint32_t *crc_table;
@@ -145,7 +145,7 @@ STATIC uint32_t crc32(uint32_t crc, const void *_buf, unsigned int len)
{
const unsigned char *buf = _buf;
-#ifdef CONFIG_DYNAMIC_CRC_TABLE
+#if defined(CONFIG_DYNAMIC_CRC_TABLE) && !defined(__PBL__)
if (!crc_table)
make_crc_table();
#endif
@@ -171,7 +171,7 @@ STATIC uint32_t crc32_no_comp(uint32_t crc, const void *_buf, unsigned int len)
{
const unsigned char *buf = _buf;
-#ifdef CONFIG_DYNAMIC_CRC_TABLE
+#if defined(CONFIG_DYNAMIC_CRC_TABLE) && !defined(__PBL__)
if (!crc_table)
make_crc_table();
#endif
---
base-commit: bef38b18eeb5d2f1fac334fb8b831e47261e099c
change-id: 20230829-crc32_in_pbl-4d824629d4e2
Best regards,
--
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