On Thu, Dec 31, 2020 at 07:08:24PM -0800, Bin Gao wrote:
> In csm mode, the bev pointer of the pci option rom was not
> added to the bootentry list, resulting in failure to boot
> from pci option rom. This patch fixed it.
> Also we enabled hw timer interrupt and clock update before
> we call the option rom's init() funtion, so the clock tick
> update at BDA address 40:6C will work during the rom's init()
> execution. Withou this change, iPXE would hang on reading BDA
> 40:6C due to the value at this address is not changed.
>
> Signed-off-by: Bin Gao <gao...@amazon.com>
> ---
> src/fw/csm.c | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/src/fw/csm.c b/src/fw/csm.c
> index 8359bcb..f64bc73 100644
> --- a/src/fw/csm.c
> +++ b/src/fw/csm.c
> @@ -19,6 +19,7 @@
> #include "std/acpi.h" // RSDP_SIGNATURE
> #include "std/bda.h" // struct bios_data_area_s
> #include "std/optionrom.h" // struct rom_header
> +#include "std/pnpbios.h" // PNP_SIGNATURE
> #include "util.h" // copy_smbios
>
> #define UINT8 u8
> @@ -219,6 +220,7 @@ handle_csm_0005(struct bregs *regs)
> {
> EFI_DISPATCH_OPROM_TABLE *table = MAKE_FLATPTR(regs->es, regs->bx);
> struct rom_header *rom;
> + struct pnp_data *pnp;
> u16 bdf;
>
> if (!CONFIG_OPTIONROMS) {
> @@ -240,11 +242,36 @@ handle_csm_0005(struct bregs *regs)
>
> rom_reserve(rom->size * 512);
>
> + // callrom() typically calls the rom's init() functions.
> + // If the rom's init() function does a delay by detecting the value
> + // at address 40:6C, it will fail because the value at 40:6C is
> + // updated only in clock_update() which is called in hw timer ISR.
> + // Thus we have to enable hw timer interrupt and set up clock before
> + // calling callrom().
> + pic_setup();
> + timer_setup();
> + clock_setup();
This doesn't look correct to me. The CSM code was originally designed
not to directly setup the PIC hardware - IIRC we don't know if the OS
is a "legacy OS" or not at this point. Maybe David has a more clear
recollection.
In any case, it would not make sense to call clock_setup() and
timer_setup() on every option rom and then again in PrepareToBoot().
-Kevin
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