On 10/27/20 3:58 PM, Keith Busch wrote: > On Tue, Oct 27, 2020 at 02:55:30PM +0100, Philippe Mathieu-Daudé wrote: >> Avoid multiple endianess conversion by using device endianess. >> >> Signed-off-by: Philippe Mathieu-Daudé <phi...@redhat.com> >> --- >> block/nvme.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/block/nvme.c b/block/nvme.c >> index e95d59d3126..be14350f959 100644 >> --- a/block/nvme.c >> +++ b/block/nvme.c >> @@ -755,7 +755,7 @@ static int nvme_init(BlockDriverState *bs, const char >> *device, int namespace, >> timeout_ms = MIN(500 * NVME_CAP_TO(cap), 30000); >> >> /* Reset device to get a clean state. */ >> - regs->cc = cpu_to_le32(le32_to_cpu(regs->cc) & 0xFE); >> + regs->cc &= const_le32(0xFE); > > This doesn't look right. The 'regs' is an MMIO address, correct? Memory > mappings use the CPU native access.
cc is little-endian uint32_t. on big-endian: const_le32(0xFE) = 0xfe000000; so: regs->cc &= 0xfe000000. Anyway this is an example of unproductive patch, as it makes things more confuse to you. Let's ignore it.