Hi Ilias,
On Mon, 26 May 2025 at 15:01, Ilias Apalodimas <ilias.apalodi...@linaro.org>
wrote:
> Hi Paul,
>
> [...]
>
>
> > bool
> >
> > +config EFI_DEBUG_SUPPORT_TABLE
> > + bool "EFI Debug Support Table"
> > + help
> > + Select this option if you want to setup the EFI Debug Support
> > + Table which is used by the debug agent or an external debugger
> to
> > + determine loaded image information in a quiescent manner.
> > +
> > menu "UEFI services"
> >
> > config EFI_GET_TIME
> > diff --git a/lib/efi_loader/efi_boottime.c
> b/lib/efi_loader/efi_boottime.c
> > index dbebb37dc04..5a4349f8679 100644
> > --- a/lib/efi_loader/efi_boottime.c
> > +++ b/lib/efi_loader/efi_boottime.c
> > @@ -4001,6 +4001,8 @@ struct efi_system_table __efi_runtime_data systab
> = {
> > .tables = NULL,
> > };
> >
> > +struct efi_system_table_pointer __efi_runtime_data * systab_pointer =
> NULL;
> > +
> > /**
> > * efi_initialize_system_table() - Initialize system table
> > *
> > @@ -4035,3 +4037,47 @@ efi_status_t efi_initialize_system_table(void)
> >
> > return ret;
> > }
> > +
> > +/**
> > + * efi_initialize_system_table() - Initialize system table pointer
> > + *
> > + * Return: status code
> > + */
> > +efi_status_t efi_initialize_system_table_pointer(void)
> > +{
> > + efi_status_t ret;
> > + const int size_4MB = 0x00400000;
> > + int pages = efi_size_in_pages(sizeof(struct
> efi_system_table_pointer));
> > + int alignment_mask = size_4MB - 1;
> > + int real_pages = pages + efi_size_in_pages(size_4MB);
> > + u64 addr;
> > + u64 aligned_addr;
> > + u32 crc32_value;
> > +
> > + /* Allocate configuration table array */
> > + ret = efi_allocate_pages(EFI_ALLOCATE_ANY_PAGES,
> > + EFI_RUNTIME_SERVICES_DATA,
> > + real_pages,
> > + &addr);
> > +
> > + if (ret != EFI_SUCCESS) {
> > + log_err("Installing EFI system table pointer failed\n");
> > + return ret;
> > + }
> > +
> > + /* alignment to 4MB boundary */
> > + aligned_addr = (addr + alignment_mask) & ~alignment_mask;
>
> efi_alloc_aligned_pages() does that for you.
> But I have similar questions to Heinrich here. Why do you need 4MB?
The alignment of this structure is 4MB. Is there a way not to allocate a
full page but still fulfill this?
The spec said. "A check-summed structure containing the physical address of
the EFI system table is created and located on a
4M aligned memory address. A hardware debugger can search memory for this
structure to determine the location of the EFI system table."
So that's why I need a page aligned with 4MB. This code is actually copied
from edk2. So I should replace it with efi_alloc_aligned_pages() right?
>
> > +
> > + systab_pointer = (struct efi_system_table_pointer *)aligned_addr;
> > + memset(systab_pointer, 0, sizeof(struct
> efi_system_table_pointer));
> > +
> > + systab_pointer->signature = EFI_SYSTEM_TABLE_SIGNATURE;
> > + systab_pointer->efi_system_table_base =
> (efi_physical_addr_t)&systab;
> > + systab_pointer->crc32 = 0;
>
> You are assigning this at the end regardless, so I guess you can skip it
> here.
>
>
Will remove.
> > + crc32_value = crc32(0,
> > + (const unsigned char *)systab_pointer,
> > + sizeof(struct efi_system_table_pointer));
> > + systab_pointer->crc32 = crc32_value;
> > +
> > + return ret;
> > +}
> > diff --git a/lib/efi_loader/efi_setup.c b/lib/efi_loader/efi_setup.c
> > index 48f91da5df7..a6b37d994f6 100644
> > --- a/lib/efi_loader/efi_setup.c
> > +++ b/lib/efi_loader/efi_setup.c
> > @@ -278,6 +278,14 @@ efi_status_t efi_init_obj_list(void)
> > if (ret != EFI_SUCCESS)
> > goto out;
> >
> > + /* Initialize system table pointer */
> > + if (IS_ENABLED(CONFIG_EFI_DEBUG_SUPPORT_TABLE)) {
> > + ret = efi_initialize_system_table_pointer();
> > + if (ret != EFI_SUCCESS) {
> > + goto out;
> > + }
> > + }
> > +
> > if (IS_ENABLED(CONFIG_EFI_ECPT)) {
> > ret = efi_ecpt_register();
> > if (ret != EFI_SUCCESS)
> > --
> > 2.39.5
> >
>
> Thanks
> /Ilias
>
