diff mbox series

[PULL,3/3] i386: load kernel on xen using DMA

Message ID 20240312142757.34141-4-anthony.perard@citrix.com (mailing list archive)
State New, archived
Headers show
Series [PULL,1/3] xen/pt: Emulate multifunction bit in header type | expand

Commit Message

Anthony PERARD March 12, 2024, 2:27 p.m. UTC 
From: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>

Kernel on Xen is loaded via fw_cfg. Previously it used non-DMA version,
which loaded the kernel (and initramfs) byte by byte. Change this
to DMA, to load in bigger chunks.
This change alone reduces load time of a (big) kernel+initramfs from
~10s down to below 1s.

This change was suggested initially here:
https://lore.kernel.org/xen-devel/20180216204031.000052e9@gmail.com/
Apparently this alone is already enough to get massive speedup.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Anthony PERARD <anthony.perard@citrix.com>
Message-Id: <20210426034709.595432-1-marmarek@invisiblethingslab.com>
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
---
 hw/i386/pc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index f5ff970acf..4f322e0856 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -718,7 +718,8 @@  void xen_load_linux(PCMachineState *pcms)
 
     assert(MACHINE(pcms)->kernel_filename != NULL);
 
-    fw_cfg = fw_cfg_init_io(FW_CFG_IO_BASE);
+    fw_cfg = fw_cfg_init_io_dma(FW_CFG_IO_BASE, FW_CFG_IO_BASE + 4,
+                                &address_space_memory);
     fw_cfg_add_i16(fw_cfg, FW_CFG_NB_CPUS, x86ms->boot_cpus);
     rom_set_fw(fw_cfg);