On 8 Jul 2023, at 04:22, 运辉崔 <cuiyunhui@xxxxxxxxxxxxx> wrote: > > Hey, > > On Sat, Jul 8, 2023 at 12:39 AM Dong Wei <Dong.Wei@xxxxxxx> wrote: >> >> >> >>> I don't think that's the limitation on RISC-V. BTW, how does OSPM find the >> >>> RSDP on ARM systems? Does it meet 5.2.5? >> >>> >> >> >> >> On Arm systems today, the ACPI RSDP is found using the UEFI Configuration Table. This is true for all Arm SystemReady compliant systems: 1) SystemReady LS: LBBRv1 is using a minimal UEFI FW to load LinuxBoot, that minimal UEFI FW is producing the UEFI Configuration Table. We are working on LBBRv2. LBBRv2 is based on Coreboot loading LinuxBoot. But we do not have a way today to get CoreBoot to produce this pointer to ACPI RSDP. Arm does not support x86 E820 BIOS interface. 2) SystemReady IR: this solution uses DT rather than ACPI. 3) SystemReady ES: this solution can use UBoot or EDK2, and it requires ACPI. Since both UBoot and EDK2 support UEFI now, so ACPI RSDP can be found using the UEFI Configuration Table. 4) SystemReady SR: this solution typically uses EDK2 and requires ACPI, so no issue finding RSDP via UEFI Configuration Table. > > Looks like ARM has a similar problem, If by “problem” you mean “there’s only one standard that I’m choosing to not follow”. > Indeed, as Ron said, many companies may encounter this issue. More > developers are embracing Coreboot. When the platform guided by > Coreboot requires ACPI support, they are faced with how to pass ACPI > RSDP to Linux. It’s called UEFI. EBBR’s requirements are pretty minimal. Please just follow the one standard. Having one standard is good for compatibility; there needs to be a very good reason beyond “I don’t like the standard” to introduce a competing one and the fragmentation that results from it that becomes shared pain for the ecosystem. Jess >> So the ACPI RSDP issue only exist if we want to remove the minimum UEFI FW and go to CoreBoot completely to load LinuxBoot. We are currently exploring how to solve that issue… >> >> >> >> -DW >> >> >> >> IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. > > Thanks, > Yunhui
