From 886d93184b894a29b0bef1f2467230a20c7a33ce Mon Sep 17 00:00:00 2001 From: Mark Salter Date: Tue, 8 Apr 2014 10:58:11 -0400 Subject: [PATCH] reopen SNP protocol for exclusive use by grub While working with pxeboot of grub on an ARM platform, I noticed very poor network performance while grub was loading a kernel and initramfs. The performance during the loading of grub itself seemed reasonable. Digging into the issue, I found that the UEFI firmware was periodically polling for network packets while grub was downloading files. This was causing timeouts and retries in the grub network stack. The solution I found was to reopen the SNP protocol for exclusive use. This forces UEFI to shutdown its use of SNP so that grub is not competing for incoming packets. Signed-off-by: Mark Salter --- grub-core/net/drivers/efi/efinet.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/grub-core/net/drivers/efi/efinet.c b/grub-core/net/drivers/efi/efinet.c index 2b344d6..a6e4c79 100644 --- a/grub-core/net/drivers/efi/efinet.c +++ b/grub-core/net/drivers/efi/efinet.c @@ -223,6 +223,7 @@ grub_efi_net_config_real (grub_efi_handle_t hnd, char **device, { struct grub_net_card *card; grub_efi_device_path_t *dp; + grub_efi_simple_network_t *net; dp = grub_efi_get_device_path (hnd); if (! dp) @@ -250,6 +251,21 @@ grub_efi_net_config_real (grub_efi_handle_t hnd, char **device, &pxe_mode->dhcp_ack, sizeof (pxe_mode->dhcp_ack), 1, device, path); + net = grub_efi_open_protocol (card->efi_handle, &net_io_guid, + GRUB_EFI_OPEN_PROTOCOL_BY_EXCLUSIVE); + if (net) { + if (net->mode->state == GRUB_EFI_NETWORK_STOPPED + && efi_call_1 (net->start, net) != GRUB_EFI_SUCCESS) + continue; + + if (net->mode->state == GRUB_EFI_NETWORK_STOPPED) + continue; + + if (net->mode->state == GRUB_EFI_NETWORK_STARTED + && efi_call_3 (net->initialize, net, 0, 0) != GRUB_EFI_SUCCESS) + continue; + card->efi_net = net; + } return; } } -- 1.8.5.3