Hi, On Thu, Jun 19, 2014 at 09:58:53PM +0100, Russell King - ARM Linux wrote: > On Thu, Jun 19, 2014 at 11:36:55PM +0300, Aaro Koskinen wrote: > > When booting v3.16-rc1 on OMAP1, I noticed strange slowness. > > E.g. initramfs unpack takes several minutes. This was caused by default > > cachepolicy getting changed from writethrough -> uncached for some reason: > > > > [ 0.000000] Booting Linux on physical CPU 0x0 > > [ 0.000000] Initializing cgroup subsys cpu > > [ 0.000000] Linux version 3.16.0-rc1-e3-los_880e+ (aaro@cooljazz) (gcc version 4.9.0 (GCC) ) #1 PREEMPT Thu Jun 19 22:51:42 EEST 2014 > > [ 0.000000] CPU: ARM925T [54029252] revision 2 (ARMv4T), cr=0000317f > > [ 0.000000] CPU: VIVT data cache, VIVT instruction cache > > [ 0.000000] Machine: Amstrad E3 (Delta) > > [ 0.000000] Ignoring memory below PHYS_OFFSET: 0x02000000-0x10000000 > > [ 0.000000] bootconsole [earlycon0] enabled > > [ 0.000000] Memory policy: Data cache uncached > > [...] > > [ 4.602732] Unpacking initramfs... > > [ 425.125093] Freeing initrd memory: 3532K (c1c00000 - c1f73000) > > > > It seems this is caused by commit: > > > > commit ca8f0b0a545f55b3dc6877cda24d609a8979c951 > > Author: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx> > > Date: Tue May 27 20:34:28 2014 +0100 > > > > ARM: ensure C page table setup code follows assembly code > > > > I can workaround this with "cachepolicy=writethrough" parameter. > > It brings up the question - proc-arm925.S contains: > > .long PMD_TYPE_SECT | \ > PMD_BIT4 | \ > PMD_SECT_AP_WRITE | \ > PMD_SECT_AP_READ > .long PMD_TYPE_SECT | \ > PMD_BIT4 | \ > PMD_SECT_AP_WRITE | \ > PMD_SECT_AP_READ > > In other words, it's telling the assembly code to setup uncached mappings > for everything, even memory. Most people want to set memory up (even at > the assembly code time) in cacheable mode... so I'd suggest adding: > > PMD_SECT_BUFFERABLE | \ > PMD_SECT_CACHEABLE | \ > > from the first. You'll find it in the .macro at the end of proc-arm925.S. > Please let me know if that works for you. So I tried the below change. But now it hangs early, even before the earlyprintk is working. :-/ A. diff --git a/arch/arm/mm/proc-arm925.S b/arch/arm/mm/proc-arm925.S index 97448c3..cb7c0e7 100644 --- a/arch/arm/mm/proc-arm925.S +++ b/arch/arm/mm/proc-arm925.S @@ -502,6 +502,8 @@ __\name\()_proc_info: .long \cpu_val .long \cpu_mask .long PMD_TYPE_SECT | \ + PMD_SECT_BUFFERABLE | \ + PMD_SECT_CACHEABLE | \ PMD_BIT4 | \ PMD_SECT_AP_WRITE | \ PMD_SECT_AP_READ -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
