[U-Boot] ELF_RELOC causes strange I-cache issues
Heiko Schocher
hs at denx.de
Thu Oct 21 11:51:57 CEST 2010
Hello Albert,
Albert Aribaud wrote:
> Wolfgang (and others who can/want),
>
> Please test this patch; it should add a complete barrier to make
> sure that all fixups are written to RAM before jumping there, and
> that no remnants subsist of the old unfixed code in the instruction
> paths. However, I cannot even do basic testing on it as I have
> no 1136 board, so I cannot rule out even basic mistakes.
>
> When this works I'll do a proper [PATCH].
>
> Amicalement,
> Albert.
>
> diff --git a/arch/arm/cpu/arm1136/start.S b/arch/arm/cpu/arm1136/start.S
> index 8b63192..f49f1de 100644
> --- a/arch/arm/cpu/arm1136/start.S
> +++ b/arch/arm/cpu/arm1136/start.S
> @@ -257,6 +257,11 @@ fixloop:
> add r2, r2, #4
> cmp r2, r3
> bne fixloop
> + /* fixups done, cleanup caches if used and prefetch buffer */
> + mov r3, #0
> + mcr p15, 0, r3, c7, c10, 4 /* data synchronization barrier */
> + mcr p15, 0, r3, c7, c5, 0 /* invalidate instruction cache */
> + mcr p15, 0, r3, c7, c5, 4 /* flush prefetch buffer */
> #endif
> #endif /* #ifndef CONFIG_SKIP_RELOCATE_UBOOT */
Actually I tried an identically patch, but didn;t help :-(
But as reading in the arm manual such a memory barrier should
not be bad here ...
BTW:
I had a fix for this problem, but I completly not understand
what it has to do with relocation (if it really is a problem
introduced through relocation ...), nor why a flush_cache
helps here, because dcache is off and only icache is on ...
diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
index f44fc4e..3e326ac 100644
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -203,6 +203,8 @@ static inline void ehci_invalidate_dcache(struct QH *qh)
static int handshake(uint32_t *ptr, uint32_t mask, uint32_t done, int usec)
{
uint32_t result;
+
+ flush_cache(0, 0);
do {
result = ehci_readl(ptr);
if (result == ~(uint32_t)0)
and the "usb read 80000000 0 1000" command works fine ...
Maybe Icache flush dosen;t work because the "ARM1136 Errata 411920
Invalidate Instruction Cache operation can fail" interferes here?
bye,
Heiko
--
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
More information about the U-Boot
mailing list