At the moment any naive attempt to boot an EFI payload that has just been loaded via "hostfs" (sandbox or semihosting) is met by a rather confusing error message: =========== VExpress64# load hostfs - $kernel_addr_r Image 52752896 bytes read in 8 ms (6.1 GiB/s) VExpress64# bootefi $kernel_addr_r No UEFI binary known at 0x80080000 =========== Actually explicitly providing the filesize: VExpress64# bootefi $kernel_addr_r:$filesize works around that problem, but the issue lies deeper: the call to efi_set_bootdev() (as done by the generic load code) bails out at some point, leaving the image_addr and image_size variables unset, which triggers this message. The problem seems to be that "-" is not understood by the code creating an UEFI device path. We could try to fix just that, but actually semihosting seems to have some explicit support in UEFI (at least it does in EDK II): there is a separate GUID for it, and hostfs is significantly different in some aspects to justify special handling.
Check for the device name being "hostfs" and create a specific UEFI device path for semihosting in this case. This uses the GUID used by EDK II for almost 15 years. This fixes the above load/bootefi sequence without requiring an explicit file size argument.
Signed-off-by: Andre Przywara andre.przywara@arm.com --- lib/efi_loader/efi_device_path.c | 34 ++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+)
diff --git a/lib/efi_loader/efi_device_path.c b/lib/efi_loader/efi_device_path.c index e2e98a39be1..b6d2074dd70 100644 --- a/lib/efi_loader/efi_device_path.c +++ b/lib/efi_loader/efi_device_path.c @@ -1079,6 +1079,35 @@ struct efi_device_path *efi_dp_from_uart(void) return buf; }
+#define SEMIHOSTING_GUID \ + EFI_GUID(0xc5b9c74a, 0x6d72, 0x4719, \ + 0x99, 0xab, 0xc5, 0x9f, 0x19, 0x90, 0x91, 0xeb) + +struct efi_device_path *efi_dp_from_semihosting(void) +{ + const struct efi_device_path_vendor smh_vendor = { + .dp = { + .type = DEVICE_PATH_TYPE_HARDWARE_DEVICE, + .sub_type = DEVICE_PATH_SUB_TYPE_VENDOR, + .length = sizeof(smh_vendor), + }, + .guid = SEMIHOSTING_GUID, + }; + void *buf, *pos; + size_t dpsize = sizeof(smh_vendor) + sizeof(END); + + buf = efi_alloc(dpsize); + if (!buf) + return NULL; + pos = buf; + memcpy(pos, &smh_vendor, sizeof(smh_vendor)); + pos += sizeof(smh_vendor); + + memcpy(pos, &END, sizeof(END)); + + return buf; +} + #ifdef CONFIG_NETDEVICES struct efi_device_path *efi_dp_from_eth(void) { @@ -1210,6 +1239,11 @@ efi_status_t efi_dp_from_name(const char *dev, const char *devnr, *device = efi_dp_from_mem(EFI_RESERVED_MEMORY_TYPE, (uintptr_t)image_addr, image_size); + } else if (!strcmp(dev, "hostfs")) { + efi_get_image_parameters(&image_addr, &image_size); + + if (device) + *device = efi_dp_from_semihosting(); } else { part = blk_get_device_part_str(dev, devnr, &desc, &fs_partition, 1);