[Qemu-devel] [PATCH RFC] Advertise IDE physical block size as 4K

[Avi Kivity]

Guests use this number as a hint for alignment and I/O request sizes.  Given
that modern disks have 4K block sizes, and cached file-backed images also
have 4K block sizes, this hint can improve guest performance.

We probably need to make this configurable depending on machine type.  It
should be the default for -M 0.13 only as it can affect guest code paths.

Signed-off-by: Avi Kivity <address@hidden>
---
 hw/ide/core.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/hw/ide/core.c b/hw/ide/core.c
index 76c3820..89fd3ce 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -164,6 +164,7 @@ static void ide_identify(IDEState *s)
     put_le16(p + 101, s->nb_sectors >> 16);
     put_le16(p + 102, s->nb_sectors >> 32);
     put_le16(p + 103, s->nb_sectors >> 48);
+    put_le16(p + 106, 0x6000 | 3); /* 8 logical sectors per physical sector */
 
     memcpy(s->identify_data, p, sizeof(s->identify_data));
     s->identify_set = 1;
-- 
1.6.5.3