On Sun, Apr 24, 2022 at 5:28 PM Guenter Roeck linux@roeck-us.net wrote:
On 4/24/22 01:52, Arnd Bergmann wrote:
On Sun, Apr 24, 2022 at 4:09 AM Guenter Roeck linux@roeck-us.net wrote: into the defconfig file, otherwise the multiplatform target defaults to an ARMv7 instead of ARMv5 build. For an OMAP15xx as in the SX1, you also need to enable CONFIG_ARCH_MULTI_V4T.
This is slightly unfortunate, but I don't see any way to avoid it, and the modified defconfig will still work fine with older kernel trees.
Yes, that works. I changed it in my configuration.
Ok, great!. I managed to boot the z2 machine with PCMCIA support and it gets around the issue with my patch, correctly detecting the CF card.
One thing I keep having to apply myself is this snippet:
diff --git a/arch/arm/mm/proc-arm925.S b/arch/arm/mm/proc-arm925.S index 0bfad62ea858..87c695703580 100644 --- a/arch/arm/mm/proc-arm925.S +++ b/arch/arm/mm/proc-arm925.S @@ -441,7 +441,6 @@ __arm925_setup:
#ifdef CONFIG_CPU_DCACHE_WRITETHROUGH mov r0, #4 @ disable write-back on caches explicitly
mcr p15, 7, r0, c15, c0, 0it does not have CONFIG_CPU_DCACHE_WRITETHROUGH enabled.
Maybe it was disabled explicitly for the sx1_defconfig because of this bug. I would think that this is required for actual sx1 hardware because the option is default-enabled for ARM925T, and that CPU core is exclusively used in OMAP15xx.
That looks like a bug in qemu. ARM925T instruction support is limited to V4T instructions. qemu doesn't have explicit 5T support. It is either V4T or V5.
I'm not entirely sure what instructions the CPU supports, but Linux treats it as ARMv4T as well, and qemu supports some of the 925t specific instructions as "ti925t" in target/arm/cpu_tcg.c, it just seems it's missing some others.
Arnd