Hi Pierre,
On Fri, Mar 15, 2024 at 12:13 PM Pierre-Clément Tosi ptosi@google.com wrote:
I had a quick look through your logs and notice that U-Boot master attempts to map addresses in the high VA range e.g.
Checking if pte fits for virt=ffffffffe4000000 [...]
while the logs that boot successfully only use the low VA range e.g.
Checking if pte fits for virt=80193000 [...]
Unless that has recently changed (since I last worked with U-Boot), U-Boot on AArch64 only supports identity mappings and therefore was only taught how to program TTBR0_ELx (i.e. is only able to map low virtual addresses). This means that the code - with or without 41e2787f5ec4 - would be unable to map addresses such as 0xffffffffe4000000.
Yes, I found it strange too. I may have done something wrong the last time I instrumented the code.
I tried it again and no longer see these unexpected high virtual addresses.
Please find the new logs here:
https://pastebin.com/raw/qF3GbJry
Now, given that 41e2787f5ec4 only affects implementation details of add_map(), I am surprised that reverting that commit changes the arguments received by the function such as virt. As a reminder, add_map() is exclusively used on mem_map:
for (i = 0; mem_map[i].size || mem_map[i].attrs; i++) add_map(&mem_map[i]);
That's the only issue preventing colibri-imx8x from booting mainline U-Boot.
If I read the U-Boot configs right i.e.
- configs/colibri-imx8x_defconfig: CONFIG_ARCH_IMX8=y
- arch/arm/mach-imx/imx8/Makefile: obj-y += cpu.o
- arch/arm/mach-imx/imx8/cpu.c: struct mm_region *mem_map = imx8_mem_map;
Correct, these are the relevant files for the i.MXQ8XP.
There is a possibility that your mem_map is getting modified by MACH-specific code. In particular, enable_caches() seems to dynamically get the MMU mappings from some RPC mechanism (see get_owned_memreg() and sc_rm_get_memreg_info()).
Could it be that whatever services those requests might be returning unexpected values? Instrumenting arch/arm/mach-imx/imx8/cpu.c and dumping mem_map (and the RPC messages) with/without the patch would help clear this up.
I tried dumping the page table entries, but could not notice anything that looked suspicious.
Please let me know if you have any suggestions.
Thanks