Huacai Chen <chenhuacai@xxxxxxxxxx> 于2023年11月22日周三 22:22写道：
>
> Hi, Yao,
>
> On Wed, Nov 22, 2023 at 4:50 PM <wangyao@xxxxxxxxxx> wrote:
> >
> > From: Wang Yao <wangyao@xxxxxxxxxx>
> >
> > Refer ot UEFI spec v2.10 section 2.3.8 LoongArch Platforms:
> >
> > The processor is in the following execution mode during boot service:
> > ...
> > The memory is in physical addressing mode. LoongArch architecture
> > defines two memory access mode, namely direct address translation
> > mode and mapped address translation mode.
> >
> > So need to change MMU translation mode before config direct mapping.
> From UEFI spec v2.10 section 2.3.8, you can also see "MMU enabled", so
> PG is already enabled in UEFI.
>
> Huacai
>
Hi,Huacai,
>From LoongArch-Vol1-v1.10-EN.pdf , DA or PG both refer to a mode enabled by MMU,
Will the UEFI firmware not use DA mode?
The UEFI spec did not specify the use of DA or PG mode, but the kernel
must use PG.
Best regards,
Ainux Wang.
> >
> > Signed-off-by: Wang Yao <wangyao@xxxxxxxxxx>
> > ---
> > drivers/firmware/efi/libstub/loongarch.c | 8 +++++++-
> > 1 file changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/firmware/efi/libstub/loongarch.c b/drivers/firmware/efi/libstub/loongarch.c
> > index 807cba2693fc..4c0a84c58f5b 100644
> > --- a/drivers/firmware/efi/libstub/loongarch.c
> > +++ b/drivers/firmware/efi/libstub/loongarch.c
> > @@ -49,7 +49,7 @@ efi_status_t efi_boot_kernel(void *handle, efi_loaded_image_t *image,
> > struct exit_boot_struct priv;
> > unsigned long desc_size;
> > efi_status_t status;
> > - u32 desc_ver;
> > + u32 desc_ver, val;
> >
> > status = efi_alloc_virtmap(&priv.runtime_map, &desc_size, &desc_ver);
> > if (status != EFI_SUCCESS) {
> > @@ -69,6 +69,12 @@ efi_status_t efi_boot_kernel(void *handle, efi_loaded_image_t *image,
> > priv.runtime_entry_count * desc_size, desc_size,
> > desc_ver, priv.runtime_map);
> >
> > + /* Change address translation mode */
> > + val = csr_read32(LOONGARCH_CSR_CRMD);
> > + val &= ~CSR_CRMD_DA;
> > + val |= CSR_CRMD_PG;
> > + csr_write32(val, LOONGARCH_CSR_CRMD);
> > +
> > /* Config Direct Mapping */
> > csr_write64(CSR_DMW0_INIT, LOONGARCH_CSR_DMWIN0);
> > csr_write64(CSR_DMW1_INIT, LOONGARCH_CSR_DMWIN1);
> > --
> > 2.27.0
> >
