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[Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash
From: |
Laszlo Ersek |
Subject: |
[Qemu-devel] [qemu PATCH] hw/i386/pc_sysfw: support more than one flash drive |
Date: |
Thu, 21 Nov 2013 23:21:01 +0100 |
This patch allows the user to usefully specify
-drive file=img_1,if=pflash,format=raw,readonly \
-drive file=img_2,if=pflash,format=raw
on the command line. The flash images will be mapped under 4G in their
reverse unit order -- that is, with their base addresses progressing
downwards, in increasing unit order.
(The unit number increases with command line order if not explicitly
specified.)
This accommodates the following use case: suppose that OVMF is split in
two parts, a writeable host file for non-volatile variable storage, and a
read-only part for bootstrap and decompressible executable code.
The binary code part would be read-only, centrally managed on the host
system, and passed in as unit 0. The variable store would be writeable,
VM-specific, and passed in as unit 1.
00000000ffe00000-00000000ffe1ffff (prio 0, R-): system.flash1
00000000ffe20000-00000000ffffffff (prio 0, R-): system.flash0
(If the guest tries to write to the flash range that is backed by the
read-only drive, bdrv_write() in pflash_update() will correctly deny the
write with -EACCES, and pflash_update() won't care, which suits us well.)
Signed-off-by: Laszlo Ersek <address@hidden>
---
hw/i386/pc_sysfw.c | 60 ++++++++++++++++++++++++++++++++++++++++--------------
1 file changed, 45 insertions(+), 15 deletions(-)
diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
index e917c83..1c3e3d6 100644
--- a/hw/i386/pc_sysfw.c
+++ b/hw/i386/pc_sysfw.c
@@ -72,35 +72,65 @@ static void pc_isa_bios_init(MemoryRegion *rom_memory,
memory_region_set_readonly(isa_bios, true);
}
+/* This function maps flash drives from 4G downward, in order of their unit
+ * numbers. Addressing within one flash drive is of course not reversed.
+ *
+ * The drive with unit number 0 is mapped at the highest address, and it is
+ * passed to pc_isa_bios_init(). Merging severral drives for isa-bios is not
+ * supported.
+ *
+ * The caller is responsible to pass in the non-NULL @pflash_drv that
+ * corresponds to the flash drive with unit number 0.
+ */
static void pc_system_flash_init(MemoryRegion *rom_memory,
DriveInfo *pflash_drv)
{
+ int unit = 0;
BlockDriverState *bdrv;
int64_t size;
- hwaddr phys_addr;
+ hwaddr phys_addr = 0x100000000ULL;
int sector_bits, sector_size;
pflash_t *system_flash;
MemoryRegion *flash_mem;
+ char name[64];
- bdrv = pflash_drv->bdrv;
- size = bdrv_getlength(pflash_drv->bdrv);
sector_bits = 12;
sector_size = 1 << sector_bits;
- if ((size % sector_size) != 0) {
- fprintf(stderr,
- "qemu: PC system firmware (pflash) must be a multiple of
0x%x\n",
- sector_size);
- exit(1);
- }
+ do {
+ bdrv = pflash_drv->bdrv;
+ size = bdrv_getlength(bdrv);
+ if ((size % sector_size) != 0) {
+ fprintf(stderr,
+ "qemu: PC system firmware (pflash segment %d) must be a "
+ "multiple of 0x%x\n", unit, sector_size);
+ exit(1);
+ }
+ if (size > phys_addr) {
+ fprintf(stderr, "qemu: pflash segments must fit under 4G "
+ "cumulatively\n");
+ exit(1);
+ }
- phys_addr = 0x100000000ULL - size;
- system_flash = pflash_cfi01_register(phys_addr, NULL, "system.flash", size,
- bdrv, sector_size, size >>
sector_bits,
- 1, 0x0000, 0x0000, 0x0000, 0x0000, 0);
- flash_mem = pflash_cfi01_get_memory(system_flash);
+ phys_addr -= size;
- pc_isa_bios_init(rom_memory, flash_mem, size);
+ /* pflash_cfi01_register() creates a deep copy of the name */
+ snprintf(name, sizeof name, "system.flash%d", unit);
+ system_flash = pflash_cfi01_register(phys_addr, NULL /* qdev */, name,
+ size, bdrv, sector_size,
+ size >> sector_bits,
+ 1 /* width */,
+ 0x0000 /* id0 */,
+ 0x0000 /* id1 */,
+ 0x0000 /* id2 */,
+ 0x0000 /* id3 */,
+ 0 /* be */);
+ if (unit == 0) {
+ flash_mem = pflash_cfi01_get_memory(system_flash);
+ pc_isa_bios_init(rom_memory, flash_mem, size);
+ }
+ pflash_drv = drive_get(IF_PFLASH, 0, ++unit);
+ } while (pflash_drv != NULL);
}
static void old_pc_system_rom_init(MemoryRegion *rom_memory, bool isapc_ram_fw)
--
1.8.3.1